Merge pull request #2 from tilal6991/master

Added search history functionality to SearchableActivity. Plus some lint stuff
Reformated every file to fit android codestyle guidelines.
Improved the readme. Added code style guidelines.
Added a context menu to each item to provide playlist-edit functionality.
Added functionality to add tracks to a CustomPlaylist.
Fixed a database bug. Albums weren't being deleted correctly.
Fixed crash in TomahawkFragment, when mCurrentPlaylist null.
Increased version number to 0.15.