cc-4661: new database tables for listener stats
- ListenerStat Model
CC-4661: Listener Statistics

- frontend part
CC-4661: Listener Statistics

- db change commit
CC-4661: Listener Statistics

-backend part working
clean up source file tailing whitespace
CC-4661: Listener Statistics

-add mount point names
CC-4661: Listener Statistics

- changes for different mount names
Merge branch 'cc-4661-listener-statistics' of dev.sourcefabric.org:airtime into cc-4661-listener-statistics
CC-4665: ReplayGain does not work for FLAC files

-fixed
don't break 80 character line limit
CC-4665: ReplayGain does not work for FLAC files

-fixed
don't break 80 character line limit
Merge branch '2.2.x' of dev.sourcefabric.org:airtime into 2.2.x
CC-4625: On tablet you cannot create a playlist, smart block or webstream

-attempt #2
Merge branch '2.2.x' of dev.sourcefabric.org:airtime into 2.2.x
CC-4665: ReplayGain does not work for FLAC files

-fixed
Merge branch '2.2.x' of dev.sourcefabric.org:airtime into 2.2.x
docstring formatting
CC-4664: Playlist/Block preview: Tracks deleted from library still get played

-fixed