add - new command line interface in distribution module

can replace Codegen and MetaGenerator classes. Provides a bit different cli interface
based on refactored pom from #541,
affects #349

```
usage: swagger <command> [<args>]

The most commonly used swagger commands are:
    generate   Generate code with chosen lang
    help       Display help information
    langs      Shows available langs
    meta       MetaGenerator. Generator for creating a new template set and configuration for Codegen.  The output will be based on the language you specify, and includes default templates to include.
 ```
  **generate** and **meta** commands have same as current cli options

modules/swagger-codegen-distribution/pom.xml

@@ -1,4 +1,5 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <parent>
         <groupId>com.wordnik</groupId>
         <artifactId>swagger-codegen-project</artifactId>
@@ -6,18 +7,14 @@
         <relativePath>../..</relativePath>
     </parent>
     <modelVersion>4.0.0</modelVersion>
-  <groupId>com.wordnik</groupId>
+
     <artifactId>swagger-codegen-distribution</artifactId>
     <packaging>jar</packaging>
+
     <name>swagger-codegen (executable)</name>
-  <version>2.1.3-M1-SNAPSHOT</version>
+
     <build>
-    <testSourceDirectory>src/test/scala</testSourceDirectory>
+        <finalName>swagger-cli</finalName>
-    <outputDirectory>target/classes</outputDirectory>
-    <testOutputDirectory>target/test-classes</testOutputDirectory>
-    <defaultGoal>install</defaultGoal>
-    <directory>target</directory>
-    <finalName>${project.artifactId}-${project.version}</finalName>
         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
@@ -25,7 +22,7 @@
                 <configuration>
                     <archive>
                         <manifest>
-              <mainClass>com.wordnik.swagger.codegen.Codegen</mainClass>
+                            <mainClass>com.wordnik.swagger.codegen.SwaggerCodegen</mainClass>
                         </manifest>
                     </archive>
                 </configuration>
@@ -36,6 +33,7 @@
                 <version>2.3</version>
                 <executions>
                     <execution>
+                        <id>reduced-pom</id>
                         <phase>package</phase>
                         <goals>
                             <goal>shade</goal>
@@ -48,14 +46,8 @@
                             </dependencyReducedPomLocation>
                         </configuration>
                     </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-shade-plugin</artifactId>
-        <version>2.3</version>
-        <executions>
                     <execution>
+                        <id>process-resources</id>
                         <phase>package</phase>
                         <goals>
                             <goal>shade</goal>
@@ -70,11 +62,34 @@
             </plugin>
         </plugins>
     </build>
+
     <dependencies>
+
         <dependency>
             <groupId>com.wordnik</groupId>
             <artifactId>swagger-codegen</artifactId>
-      <version>${project.parent.version}</version>
+            <version>${project.version}</version>
         </dependency>
+
+        <!--https://github.com/airlift/airline-->
+        <dependency>
+            <groupId>io.airlift</groupId>
+            <artifactId>airline</artifactId>
+            <version>0.7</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.googlecode.lambdaj</groupId>
+            <artifactId>lambdaj</artifactId>
+            <version>2.3.3</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>${slf4j-version}</version>
+        </dependency>
+
     </dependencies>
+
 </project>

modules/swagger-codegen-distribution/src/main/java/com/wordnik/swagger/codegen/SwaggerCodegen.java

@@ -0,0 +1,30 @@
+package com.wordnik.swagger.codegen;
+
+import com.wordnik.swagger.codegen.cmd.Generate;
+import com.wordnik.swagger.codegen.cmd.Langs;
+import com.wordnik.swagger.codegen.cmd.Meta;
+import io.airlift.airline.Cli;
+import io.airlift.airline.Help;
+
+/**
+ * User: lanwen
+ * Date: 24.03.15
+ * Time: 17:56
+ */
+public class SwaggerCodegen {
+
+
+    public static void main(String[] args) {
+        Cli.CliBuilder<Runnable> builder = Cli.<Runnable>builder("swagger")
+                .withDescription("Swagger code generator CLI. More info on swagger.io")
+                .withDefaultCommand(Langs.class)
+                .withCommands(
+                        Generate.class,
+                        Meta.class,
+                        Langs.class,
+                        Help.class
+                );
+
+        builder.build().parse(args).run();
+    }
+}

modules/swagger-codegen-distribution/src/main/java/com/wordnik/swagger/codegen/cmd/Generate.java

@@ -0,0 +1,120 @@
+package com.wordnik.swagger.codegen.cmd;
+
+import com.wordnik.swagger.codegen.ClientOptInput;
+import com.wordnik.swagger.codegen.ClientOpts;
+import com.wordnik.swagger.codegen.CodegenConfig;
+import com.wordnik.swagger.codegen.DefaultGenerator;
+import com.wordnik.swagger.models.Swagger;
+import io.airlift.airline.Command;
+import io.airlift.airline.Option;
+import io.swagger.parser.SwaggerParser;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.util.ServiceLoader;
+
+import static java.util.ServiceLoader.load;
+import static org.apache.commons.lang3.StringUtils.isNotEmpty;
+
+/**
+ * User: lanwen
+ * Date: 24.03.15
+ * Time: 20:22
+ */
+
+@Command(name = "generate", description = "Generate code with chosen lang")
+public class Generate implements Runnable {
+
+    public static final Logger LOG = LoggerFactory.getLogger(Generate.class);
+
+    public static final String TEMPLATE_DIR_PARAM = "templateDir";
+
+    @Option(name = {"-v", "--verbose"}, description = "verbose mode")
+    public boolean verbose;
+
+    @Option(name = {"-l", "--lang"}, title = "language", required = true,
+            description = "client language to generate (maybe class name in classpath, required)")
+    public String lang;
+
+    @Option(name = {"-o", "--output"}, title = "output directory",
+            description = "where to write the generated files (current dir by default)")
+    public String output = "";
+
+    @Option(name = {"-i", "--input-spec"}, title = "spec file", required = true,
+            description = "location of the swagger spec, as URL or file (required)")
+    public String spec;
+
+    @Option(name = {"-t", "--template-dir"}, title = "template directory",
+            description = "folder containing the template files")
+    public String templateDir;
+
+    @Option(name = {"-a", "--auth"}, title = "authorization",
+            description = "adds authorization headers when fetching the swagger definitions remotely. " +
+                    "Pass in a URL-encoded string of name:header with a comma separating multiple values")
+    public String auth;
+
+    @Override
+    public void run() {
+        verbosed(verbose);
+
+        ClientOptInput input = new ClientOptInput();
+
+        if (isNotEmpty(auth)) {
+            input.setAuth(auth);
+        }
+
+        CodegenConfig config = forName(lang);
+        config.setOutputDir(new File(output).getAbsolutePath());
+
+        if (null != templateDir) {
+            config.additionalProperties().put(TEMPLATE_DIR_PARAM, new File(templateDir).getAbsolutePath());
+        }
+
+        input.setConfig(config);
+
+        Swagger swagger = new SwaggerParser().read(spec, input.getAuthorizationValues(), true);
+        new DefaultGenerator().opts(input.opts(new ClientOpts()).swagger(swagger)).generate();
+    }
+
+    /**
+     * If true parameter, adds system properties which enables debug mode in generator
+     * @param verbose - if true, enables debug mode
+     */
+    private void verbosed(boolean verbose) {
+        if (!verbose) {
+            return;
+        }
+        LOG.info("\nVERBOSE MODE: ON. Additional debug options are injected" +
+                "\n - [debugSwagger] prints the swagger specification as interpreted by the codegen" +
+                "\n - [debugModels] prints models passed to the template engine" +
+                "\n - [debugOperations] prints operations passed to the template engine" +
+                "\n - [debugSupportingFiles] prints additional data passed to the template engine");
+
+        System.setProperty("debugSwagger", "");
+        System.setProperty("debugModels", "");
+        System.setProperty("debugOperations", "");
+        System.setProperty("debugSupportingFiles", "");
+    }
+
+    /**
+     * Tries to load config class with SPI first, then with class name directly from classpath
+     * @param name name of config, or full qualified class name in classpath
+     * @return config class
+     */
+    private static CodegenConfig forName(String name) {
+        ServiceLoader<CodegenConfig> loader = load(CodegenConfig.class);
+        for (CodegenConfig config : loader) {
+            if (config.getName().equals(name)) {
+                return config;
+            }
+        }
+
+        // else try to load directly
+        try {
+            return (CodegenConfig) Class.forName(name).newInstance();
+        } catch (Exception e) {
+            throw new RuntimeException("Can't load config class with name ".concat(name), e);
+        }
+    }
+}

modules/swagger-codegen-distribution/src/main/java/com/wordnik/swagger/codegen/cmd/Langs.java

@@ -0,0 +1,23 @@
+package com.wordnik.swagger.codegen.cmd;
+
+import ch.lambdaj.collection.LambdaIterable;
+import com.wordnik.swagger.codegen.CodegenConfig;
+import io.airlift.airline.Command;
+
+import static ch.lambdaj.Lambda.on;
+import static ch.lambdaj.collection.LambdaCollections.with;
+import static java.util.ServiceLoader.load;
+
+/**
+ * User: lanwen
+ * Date: 24.03.15
+ * Time: 20:25
+ */
+@Command(name = "langs", description = "Shows available langs")
+public class Langs implements Runnable {
+    @Override
+    public void run() {
+        LambdaIterable<String> langs = with(load(CodegenConfig.class)).extract(on(CodegenConfig.class).getName());
+        System.out.printf("Available languages: %s%n", langs);
+    }
+}

modules/swagger-codegen-distribution/src/main/java/com/wordnik/swagger/codegen/cmd/Meta.java

@@ -0,0 +1,144 @@
+package com.wordnik.swagger.codegen.cmd;
+
+import ch.lambdaj.function.convert.Converter;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.samskivert.mustache.Mustache;
+import com.wordnik.swagger.codegen.DefaultGenerator;
+import com.wordnik.swagger.codegen.SupportingFile;
+import io.airlift.airline.Command;
+import io.airlift.airline.Option;
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.Reader;
+import java.util.List;
+import java.util.Map;
+
+import static ch.lambdaj.collection.LambdaCollections.with;
+import static com.google.common.base.Joiner.on;
+
+/**
+ * User: lanwen
+ * Date: 24.03.15
+ * Time: 20:22
+ */
+
+@Command(name = "meta", description = "MetaGenerator. Generator for creating a new template set " +
+        "and configuration for Codegen.  The output will be based on the language you " +
+        "specify, and includes default templates to include.")
+public class Meta implements Runnable {
+
+    public static final Logger LOG = LoggerFactory.getLogger(Meta.class);
+
+    public static final String TEMPLATE_DIR_CLASSPATH = "codegen";
+    public static final String MUSTACHE_EXTENSION = ".mustache";
+
+    @Option(name = {"-o", "--output"}, title = "output directory",
+            description = "where to write the generated files (current dir by default)")
+    public String outputFolder = "";
+
+    @Option(name = {"-n", "--name"}, title = "name",
+            description = "the human-readable name of the generator")
+    public String name = "default";
+
+    @Option(name = {"-p", "--package"}, title = "package",
+            description = "the package to put the main class into (defaults to com.wordnik.swagger.codegen)")
+    public String targetPackage = "com.wordnik.swagger.codegen";
+
+    @Override
+    public void run() {
+        final File targetDir = new File(outputFolder);
+        LOG.info("writing to folder [{}]", targetDir.getAbsolutePath());
+
+        String mainClass = StringUtils.capitalize(name) + "Generator";
+
+        List<SupportingFile> supportingFiles = ImmutableList.of(
+                new SupportingFile("pom.mustache", "", "pom.xml"),
+                new SupportingFile("generatorClass.mustache",
+                        on(File.separator).join("src/main/java", asPath(targetPackage)), mainClass.concat(".java")),
+                new SupportingFile("README.mustache", "", "README.md"),
+                new SupportingFile("api.template", "src/main/resources" + File.separator + name, "api.mustache"),
+                new SupportingFile("model.template", "src/main/resources" + File.separator + name, "model.mustache"),
+                new SupportingFile("services.mustache",
+                        "src/main/resources/META-INF/services", "com.wordnik.swagger.codegen.CodegenConfig")
+        );
+
+        Map<String, Object> data = new ImmutableMap.Builder<String, Object>()
+                .put("generatorPackage", targetPackage)
+                .put("generatorClass", mainClass)
+                .put("name", name)
+                .put("fullyQualifiedGeneratorClass", targetPackage + "." + mainClass).build();
+
+
+        with(supportingFiles).convert(processFiles(targetDir, data));
+    }
+
+    /**
+     * Converter method to process supporting files: execute with mustache,
+     * or simply copy to destination directory
+     * @param targetDir - destination directory
+     * @param data - map with additional params needed to process templates
+     * @return converter object to pass to lambdaj
+     */
+    private Converter<SupportingFile, File> processFiles(final File targetDir, final Map<String, Object> data) {
+        return new Converter<SupportingFile, File>() {
+            private DefaultGenerator generator = new DefaultGenerator();
+
+            @Override
+            public File convert(SupportingFile support) {
+                try {
+                    File destinationFolder = new File(new File(targetDir.getAbsolutePath()), support.folder);
+                    File outputFile = new File(destinationFolder, support.destinationFilename);
+
+                    String template = generator
+                            .readTemplate(new File(TEMPLATE_DIR_CLASSPATH, support.templateFile).getPath());
+                    String formatted = template;
+
+                    if (support.templateFile.endsWith(MUSTACHE_EXTENSION)) {
+                        LOG.info("writing file to {}", outputFile.getAbsolutePath());
+                        formatted = Mustache.compiler().withLoader(loader(generator))
+                                .defaultValue("")
+                                .compile(template)
+                                .execute(data);
+                    } else {
+                        LOG.info("copying file to {}", outputFile.getAbsolutePath());
+                    }
+
+                    FileUtils.writeStringToFile(outputFile, formatted);
+                    return outputFile;
+
+                } catch (IOException e) {
+                    throw new RuntimeException("Can't generate project", e);
+                }
+            }
+        };
+    }
+
+    /**
+     * Creates mustache loader for template using classpath loader
+     * @param generator - class with reader getter
+     * @return loader for template
+     */
+    private Mustache.TemplateLoader loader(final DefaultGenerator generator) {
+        return new Mustache.TemplateLoader() {
+            public Reader getTemplate(String name) {
+                return generator.getTemplateReader(TEMPLATE_DIR_CLASSPATH
+                        + File.separator + name.concat(MUSTACHE_EXTENSION));
+            }
+        };
+    }
+
+    /**
+     * Converts package name to path on file system
+     * @param packageName - package name to convert
+     * @return relative path
+     */
+    private String asPath(String packageName) {
+        return packageName.replace(".", File.separator);
+    }
+}