Offer list of existing playlists when saving

Fixes #454
Merge pull request #457 from hurzl/playlists

Offer list of existing playlists when saving
add setting
add strings
add PlaylistAlbum
add size() and hasText() to AbstractPlaylistMusic
PlaylistFragment: import
PlaylistFragment: add vars

Conflicts:
	MPDroid/src/com/namelessdev/mpdroid/fragments/PlaylistFragment.java
PlaylistFragment: playlistAlbumWithSongId
PlaylistFragment: onActionItemClicked

Conflicts:
	MPDroid/src/com/namelessdev/mpdroid/fragments/PlaylistFragment.java
PlaylistFragment: update
PlaylistFragment: scrollToNowPlaying
PlaylistFragment: trackChanged
PlaylistFragment: onDrop
PlaylistFragment: itemMenuButtonListener

Conflicts:
	MPDroid/src/com/namelessdev/mpdroid/fragments/PlaylistFragment.java
PlaylistFragment: R.id.PLCX_playNext
PlaylistFragment: PLCX_moveFirst
PlaylistFragment: PLCX_moveLast
PlaylistFragment: PLCX_removeFromPlaylist
PlaylistFragment: PLCX_goToArtist