Automatically tracks IAP purchases

* IAP purchases are now automatically tracked so you can better segment your users.
   - sendPurchase is now deprecated and currently does nothing since they are now automatic.
* iOS fix - Issue where going to the homescreen after watching a video ad with AdColony would crash the app.
   - The fix improves the handling of method swizzling in general which means better compatibility with other libraries too.
* Android feature - The notification icon can now be different than your app icon by creating an image file named gamethrive_statusbar_icon_default in your drawable dpi folders.