Migrate project for Gradle build system.
Automatically format code and organize imports (no code change here!).
Migrate application version settings to Gradle.
Rename output files.
Enable signing with Gradle.
Customize debug build type.
Fix ProGuard error for ActionBarSherlock.

+ See: https://github.com/JakeWharton/ActionBarSherlock/issues/1001
Rename and update README.
Remove Android Studio import summary.
Update build tools to v.21.1.1.
Update Gradle plug-in to v.0.14.1.

+ Update deprecated configuration.
Merge pull request #45 from johnjohndoe/gradle-migration-38

Gradle / Android Studio migration