Add support for creating a jar with Ant

Including a whole project just for some Java files is unnecessary - there should be at least a jar (ideally a maven release) instead. 

Instructions for building jar:

1) clone the project and run `android update project -p . --target android-8` in the project directory
2) Run `ant release`
3) Run `ant jar`

You will need to add a dependency on Google Play Services to your main project e.g. compile `compile 'com.google.android.gms:play-services:5.+'`

If Google Play Services was not found you'll notice a message show up in your log:
`Unable to get Google Play Services Advertising ID at start time`