Remove peer connection and signaling calls from UI thread.

- Add separate looper threads for peer connection and websocket
signaling classes.
- To improve the connection speed start peer connection factory
initialization once EGL context is ready in parallel with the room
connection.
- Add asynchronious http request class and start using it in
webscoket signaling and room parameters extractor.
- Add helper looper based executor class.
- Port some of henrika changes from
https://webrtc-codereview.appspot.com/36629004/ to fix sensor
crashes on non L devices - will remove the change if CL will
be submitted soon.

R=jiayl@webrtc.org, wzh@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/41369004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@8006 4adac7df-926f-26a2-2b94-8c16560cd09d

talk/examples/android/src/org/appspot/apprtc/AppRTCAudioManager.java

@@ -27,6 +27,8 @@
 
 package org.appspot.apprtc;
 
+import org.appspot.apprtc.util.AppRTCUtils;
+
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
@@ -35,8 +37,6 @@ import android.content.pm.PackageManager;
 import android.media.AudioManager;
 import android.util.Log;
 
-import org.appspot.apprtc.util.AppRTCUtils;
-
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;