Lockscreen wallpaper for themes

Change-Id: If77b97301c5bfebd94b193fe9a54e676e678d3ed

Conflicts:
	core/java/android/content/pm/ThemeUtils.java
	services/java/com/android/server/ThemeService.java

Conflicts:
	packages/Keyguard/src/com/android/keyguard/KeyguardViewManager.java
	services/java/com/android/server/ThemeService.java