frameworks: add keyguard wallpaper functionality to WallpaperManager

Adapted for cm-12.

Change-Id: I0eb1b5578b705c2ade4c0772fa86e09478b9f73e
Signed-off-by: Roman Birg <roman@cyngn.com>
Move CAF strings

Change-Id: I5d8bbf7075d1d24391bbbf0d190a33cc097c40a6

Conflicts:
	packages/SystemUI/res/values/cm_strings.xml