[ReactNative] Refactor BatchedBridge and MessageQueue

Summary:
@public

The current implementation of `MessageQueue` is huge, over-complicated and spread
across `MethodQueue`, `MethodQueueMixin`, `BatchedBridge` and `BatchedBridgeFactory`

Refactored in a simpler way, were it's just a `MessageQueue` class and `BatchedBridge`
is only an instance of it.

Test Plan:
I had to make some updates to the tests, but no real update to the native side.
There's also tests covering the `remoteAsync` methods, and more integration tests for UIExplorer.
Verified whats being used by Android, and it should be safe, also tests Android tests have been pretty reliable.

Manually testing: Create a big hierarchy, like `<ListView>` example. Use the `TimerMixin` example to generate multiple calls.
Test the failure callback on the `Geolocation` example.

All the calls go through this entry point, so it's hard to miss if it's broken.

debugger.html

@@ -48,10 +48,11 @@ var messageHandlers = {
     loadScript(message.url, sendReply.bind(null, null));
   },
   'executeJSCall': function(message, sendReply) {
-    var returnValue = [[], [], [], [], []];
+    var returnValue = null;
     try {
       if (window && window.require) {
-        returnValue = window.require(message.moduleName)[message.moduleMethod].apply(null, message.arguments);
+        var module = window.require(message.moduleName);
+        returnValue = module[message.moduleMethod].apply(module, message.arguments);
       }
     } finally {
       sendReply(JSON.stringify(returnValue));