Move code to Android Studio

- Relocate directory structure.

- Port MapDemoActivity to new Google Play API.

- Add Google Play to Gradle file.

![image](https://cloud.githubusercontent.com/assets/326857/5567167/337e42bc-8ef3-11e4-86b8-f96934d703df.png)


@nesquena 
@nesquena turns out build/** does not exclude app/build/**, so we either put it there or just don't use wildcards.