Adding the possibility to receive the callback to a thread different from the main one to all response methods.

Source/ResponseSerialization.swift

@@ -176,8 +176,12 @@ extension Request {
 
         - returns: The request.
     */
-    public func responseData(completionHandler: Response<NSData, NSError> -> Void) -> Self {
-        return response(responseSerializer: Request.dataResponseSerializer(), completionHandler: completionHandler)
+    public func responseData(
+        queue queue: dispatch_queue_t? = nil,
+        completionHandler: Response<NSData, NSError> -> Void)
+        -> Self
+    {
+        return response(queue: queue, responseSerializer: Request.dataResponseSerializer(), completionHandler: completionHandler)
     }
 }
 
@@ -240,11 +244,13 @@ extension Request {
         - returns: The request.
     */
     public func responseString(
-        encoding encoding: NSStringEncoding? = nil,
+        queue queue: dispatch_queue_t? = nil,
+        encoding: NSStringEncoding? = nil,
         completionHandler: Response<String, NSError> -> Void)
         -> Self
     {
         return response(
+            queue: queue,
             responseSerializer: Request.stringResponseSerializer(encoding: encoding),
             completionHandler: completionHandler
         )
@@ -296,11 +302,13 @@ extension Request {
         - returns: The request.
     */
     public func responseJSON(
-        options options: NSJSONReadingOptions = .AllowFragments,
+        queue queue: dispatch_queue_t? = nil,
+        options: NSJSONReadingOptions = .AllowFragments,
         completionHandler: Response<AnyObject, NSError> -> Void)
         -> Self
     {
         return response(
+            queue: queue,
             responseSerializer: Request.JSONResponseSerializer(options: options),
             completionHandler: completionHandler
         )
@@ -354,11 +362,13 @@ extension Request {
         - returns: The request.
     */
     public func responsePropertyList(
-        options options: NSPropertyListReadOptions = NSPropertyListReadOptions(),
+        queue queue: dispatch_queue_t? = nil,
+        options: NSPropertyListReadOptions = NSPropertyListReadOptions(),
         completionHandler: Response<AnyObject, NSError> -> Void)
         -> Self
     {
         return response(
+            queue: queue,
             responseSerializer: Request.propertyListResponseSerializer(options: options),
             completionHandler: completionHandler
         )