Frameworks: Lockscreen custom wallpaper (1/2)

kitkat now has code for a custom wallpaper image.

Using that code set a switch case to set the custom background between
  - Custom Wallpaper
  - Default background

This way allows the same overlay shadow thats set on the keyguard when
its the defualt way.

Change-Id: I98fde63ef9f3c0a5f334cd9a97b237a6f99c57f6
Lockscreen: Fix SystemUI crash on initial selection of Custom Background.

Change-Id: I8df4984f4b90d211baa888d380a95fc00a85d1ad