Refresh endpoint

This PR contains the old #8 and replace MemoryStore by SQLStore to prevent the JVM kill MemoryStore

You can test it using [GDrive](https://github.com/danielpassos/aerogear-android-cookbook/tree/GDrive/GDrive)

You will need build these agdroid modules locally 

* [core](github.com/aerogear/aerogear-android-core); 
* [pipe](github.com/aerogear/aerogear-android-pipe);
* [security](https://github.com/aerogear/aerogear-android-security); 
* [store](github.com/aerogear/aerogear-android-store)