jni: simplify android_main

We no longer have to send this stuff to our jni handlers.

Also scope the objects we create so that they are explicitly destroyed before
we exit.
jni: cosmetics: indent after scoping CXBMCApp and CEventLoop
jni: show the intent action that started us
jni: fix headers
jni: remove old files
jni: rename OnReceive to match what the helper lib expects

Also print events as they come in
jni: pass the current intent along to our activity
jni: remove the hard-coded receiver

We register for everything dynamically in native code now
jni: fix AE build after adding new jni lib
jni: add a quick readme