Simplification & Refactoring
     - Simplification thanks to JAudioTagger API
     - Refactoring package
     - Add helpers
     - Add comments
     - minor improvements
Minor improvment provide by SonarQube.
Minor improvement.
Minor improvment provide by SonarQube.
Improve list UI
Refactor ArtworkHelper to ThumbnailService
Add Source Folder to Shared Preferences.
Minor improvements.
Images modification :
    - song
    - folder
I have added the last song picture for the format hdpi.
Bug fixing: In the settings the default value for source folder was fill by the wrong resource.
Bug fixing: Data change without notify the adapter.
Optimisation improvements.
Add folder browsing.
Some comments and improvement.
 The loader manager can remove finished loader.
AsyncTask can execute simultaneously.
Add comment and sonar improvements
Add progress bar.
Set up material theme.
Progress bar optimisation : animation.
List view optimisation : Google's AsyncDrawable pattern.
Merge remote-tracking branch 'origin/res/ui' into feat/localMusicAccess

Conflicts:
	app/build.gradle