Play services auto setup

This CL adds auto-detection of the Google Play Services SDK for Android apps. We check to see if Play Services is listed in the remote SDKs. If that's the case we know it's not installed or is out-of-date.

When detected, we automatically copy the SDK into the Android library and do the setup necessary to add it to the Android project.

I've currently skipped setting up services on Windows since my paths will be incorrect. This should work correctly on Linux and Mac.

BUG=#9