lockscreen music controls

port (found in Carbon) of CM feature to hide/enable music widget on lockscreen
written by Danny Baumann <dannybaumann@web.de>

Change-Id: I9ecff439526bfcdaa9352a9dcc59cce5586f13ec
clean up more stains

Change-Id: I9e406f11be28596dbbbc05c24f1c615255d828dd