[Swift] Use the latest Alamofire (3.4.1)

This commit updates the Swift client templates to be compatible with the
latest version of Alamofire. It bumps the dependency version in the
podspec and names the argument when calling `responseData`. We found
that XCode was having trouble with the overloaded methods and needed the
named argument for hinting.

modules/swagger-codegen/src/main/resources/swift/AlamofireImplementations.mustache

@@ -90,7 +90,7 @@ class AlamofireRequestBuilder<T>: RequestBuilder<T> {
 
         switch T.self {
         case is NSData.Type:
-            validatedRequest.responseData({ (dataResponse) in
+            validatedRequest.responseData(completionHandler: { (dataResponse) in
                 cleanupRequest()
 
                 if (dataResponse.result.isFailure) {

modules/swagger-codegen/src/main/resources/swift/Podspec.mustache

@@ -16,5 +16,5 @@ Pod::Spec.new do |s|
   s.documentation_url = '{{podDocumentationURL}}'{{/podDocumentationURL}}
   s.source_files = '{{projectName}}/Classes/Swaggers/**/*.swift'{{#usePromiseKit}}
   s.dependency 'PromiseKit', '~> 3.1.1'{{/usePromiseKit}}
-  s.dependency 'Alamofire', '~> 3.1.5'
+  s.dependency 'Alamofire', '~> 3.4.1'
 end