[TIMOB-2170] Android: regression in Ti.App.fireEvent from within WebView context on 1.5 trunk

In testing StatusNet Mobile against the new 1.5 Android code in trunk, I've found that custom application events fired from JavaScript code running within a WebView no longer work. This is needed for our app to communicate between the main UI code and the WebView that displays our message timelines.

I believe I've tracked it to commit 7926eda7aad2fa2073aad2849f4ed890c5807e00

This commit removes AppModule.fireEvent(), which used to override the default KrollProxy event handler function with a call to fireAppEvent() on the current app retrieved from the current context. I believe that breaks the code in TiWebViewBinding.AppBinding.fireEvent(), which calls fireEvent() directly on a private AppModule instance.

With the AppModule.fireEvent() hack removed, it looks like that'll just fire events on the individual instance and not call the global application.