Trebuchet: add lockscreen wallpaper picker

Change-Id: Ic4f2589924a3c61b676db907f08108286dc45c29
Signed-off-by: Roman Birg <roman@cyngn.com>
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_packages_apps_Trebuchet into cd-4.4