Create Playlist / Add to Playlist user experience upgrade.

Adds songs to existing playlists from my files > audio.
MenuAdapter keeps a weak reference of context
added getContext() method to MenuAction
Some misc fixes on apollo to avoid possible null pointers, refactors.
Creates new playlist and ads selected tracks to it.
address case with playlist of existing name recursively. move getPlaylists() to MusicUtils.
adds song to playlist from player window.
default artwork image updated everywhere.

Add to playlist actions added to player action bar menus, playlists still not refreshed. default artworks updated.
Merge pull request #175 from gubatron/my-files-add-to-playlist

Create Playlist / Add to Playlist user experience upgrade.