Enable theming lockscreen wallpaper via ThemeManager [1/2].

PS2:
Correctly handle excluding wallpapers.

PS3:
Typo in commit message

Change-Id: I1dcb5b815ac77ce050ad7412e9bbe05e9e8f7d49
Merge "Enable theming lockscreen wallpaper via ThemeManager [1/2]." into jellybean-mr2.1