Beta Version of SDK for Android

Refs #1
@lttldrgn I was aware that Tracker is not thread safe, but on the other hand I don't want to use a lot synchronized blocks in order to avoid potential deadlocks. Maybe we should use [ConcurrentLinkedQueue](http://developer.android.com/reference/java/util/concurrent/ConcurrentLinkedQueue.html) instead of ArrayList, what do You think?