Add Gradle support

[KarlNosworthy]

Add support for the new Gradle based Android build system.

This could include the standard directory structure and simple build.gradle file.

There may be a current conflict with Roboelectric - which I believe has some issues with the new gradle based system but is being currently investigated - once these issues have been resolved I think this would be a fantastic addition.

[a-thomas]

Indeed, it could be great to support Gradle.
I have not try it yet.

[a-thomas]

If you are motivated, feel free to implement it :)

[jeremiemartinez]

Given the Google I/O, it seems legit :P

[coreydowning]

+1 for progress

[sealskej]

+1

[kenyee]

If you do this, it makes the Eclipse Android plugin not work properly (at least until Google updates it to support the standard Gradle directory structure which they should have before announcing Android Studio support IMHO)-:

You can migrate it to Android Studio by doing a file/export in Eclipse and it'll generate the build.gradle for you, and then you can get the project into Android Studio.

[arvindstutzen]

+1