Updated German translation
Updated Norwegian bokmål translation
Tajik translation updated
Updated Traditional Chinese translation(Hong Kong and Taiwan)
Updated Slovenian translation
Updated slovak translation
Updated slovak translation
Added da to list of languages
Updated Danish translation
Updated Indonesian translation
Updated Hungarian translation
Added British English translation
Add support for notifications

Add a NotificationManager object that watches the Player and
keeps a resident notification to control the application.

https://bugzilla.gnome.org/show_bug.cgi?id=702377
notification: Get current media directly from player
notification: Fix crash if artist or album is unknown
po: Add gnomemusic/notification.py to POTFILES.in
Runtime check for libnotify
Runtime check for libnotify