framework: Custom lock screen background [1/2]

Patch Set 1:	* port the custom lock screen feature from
		  ics (http://review.cyanogenmod.org/#/c/16915)

		* thanks to Danny Baumann, who reworked the
		  framework part to work after Jelly Bean 4.2
		  lockscreen changes

Patch Set 2-3:	* remove obsolete files

Patch Set 4:	* revert XML changes (left copyright cleanup)

Change-Id: I800506a9f9e001f659ee29b8b2dbe3464e5198f9