APPRTCDemo(objc): Remove regex parsing in favor of JSON struct.

Also some cleanup/refactoring of APPRTCAppClient.

R=fischman@webrtc.org, glaznev@webrtc.org
BUG=3407

Review URL: https://webrtc-codereview.appspot.com/18499004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6362 4adac7df-926f-26a2-2b94-8c16560cd09d

talk/examples/objc/AppRTCDemo/GAEChannelClient.h

@@ -44,6 +44,9 @@
 // application and AppEngine.
 @interface GAEChannelClient : NSObject
 
-- (id)initWithToken:(NSString*)token delegate:(id<GAEMessageHandler>)delegate;
+@property(nonatomic, weak) id<GAEMessageHandler> delegate;
+
+- (instancetype)initWithToken:(NSString*)token
+                     delegate:(id<GAEMessageHandler>)delegate;
 
 @end