AppRTCDemo(iOS): prefer ISAC as audio codec

This makes audio flow well bidirectionally to an iPod Touch (5th gen).
Also:
- Update to new turnserver JSON style:
  - separate username field
  - multiple URLs for the same server (e.g. both UDP & TCP)
- Added more explicit logging for ICE Connected since it's useful for debugging
- Give focus to the input field on app launch since that's the only useful
  thing to have focus on, anyway.
- Fix minor typos
- Cleaned up trailing whitespace and hard tabs

BUG=2191
R=wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2127004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4687 4adac7df-926f-26a2-2b94-8c16560cd09d

talk/examples/ios/AppRTCDemo/APPRTCViewController.m

@@ -36,6 +36,7 @@
 - (void)viewDidLoad {
   [super viewDidLoad];
   self.textField.delegate = self;
+  [self.textField becomeFirstResponder];
 }
 
 - (void)displayText:(NSString *)text {