Introduce NodeJS codegen for Google Cloud Functions. (#4406)

* Another approach: extending NodeJS server to support GCF.

This does not add a new language, but adding some client options
to support Google Cloud Functions (GCF).

* Add URLs for how to deploy the generated code.

Adds the client options help message and the README.md file.

samples/server/petstore/nodejs-google-cloud-functions/controllers/StoreService.js

@@ -0,0 +1,77 @@
+'use strict';
+
+exports.deleteOrder = function(args, res, next) {
+  /**
+   * parameters expected in the args:
+  * orderId (String)
+  **/
+  // no response value expected for this operation
+  res.end();
+}
+
+exports.getInventory = function(args, res, next) {
+  /**
+   * parameters expected in the args:
+  **/
+    var examples = {};
+  examples['application/json'] = {
+  "key" : 123
+};
+  if(Object.keys(examples).length > 0) {
+    res.setHeader('Content-Type', 'application/json');
+    res.end(JSON.stringify(examples[Object.keys(examples)[0]] || {}, null, 2));
+  }
+  else {
+    res.end();
+  }
+  
+}
+
+exports.getOrderById = function(args, res, next) {
+  /**
+   * parameters expected in the args:
+  * orderId (Long)
+  **/
+    var examples = {};
+  examples['application/json'] = {
+  "petId" : 123456789,
+  "quantity" : 123,
+  "id" : 123456789,
+  "shipDate" : "2000-01-23T04:56:07.000+00:00",
+  "complete" : true,
+  "status" : "aeiou"
+};
+  if(Object.keys(examples).length > 0) {
+    res.setHeader('Content-Type', 'application/json');
+    res.end(JSON.stringify(examples[Object.keys(examples)[0]] || {}, null, 2));
+  }
+  else {
+    res.end();
+  }
+  
+}
+
+exports.placeOrder = function(args, res, next) {
+  /**
+   * parameters expected in the args:
+  * body (Order)
+  **/
+    var examples = {};
+  examples['application/json'] = {
+  "petId" : 123456789,
+  "quantity" : 123,
+  "id" : 123456789,
+  "shipDate" : "2000-01-23T04:56:07.000+00:00",
+  "complete" : true,
+  "status" : "aeiou"
+};
+  if(Object.keys(examples).length > 0) {
+    res.setHeader('Content-Type', 'application/json');
+    res.end(JSON.stringify(examples[Object.keys(examples)[0]] || {}, null, 2));
+  }
+  else {
+    res.end();
+  }
+  
+}
+