[1/2] Base: Lockscreen wallpaper

Allows user to choose a custom wallpaper for lockscreen
Changeable through Settings->Display->Wallpaper->Lockscreen
Or Settings->SecuritySettings->Lockscreen->CustomBackground

OmniGears: https://gerrit.omnirom.org/6574

Change-Id: I97a6d31ef8915bc3a12b48426afbd6d0b92a41f6

Conflicts:
	core/java/android/provider/Settings.java
	packages/Keyguard/src/com/android/keyguard/KeyguardViewManager.java

Conflicts:
	core/java/android/provider/Settings.java
	packages/Keyguard/src/com/android/keyguard/KeyguardViewManager.java
Revert "[1/2] Base: Lockscreen wallpaper"

This reverts commit 74c53d27c1bc56f454137038fe159a94d4fcc48f.
Wallpaper lockscreen

Accessible via launcher wallpaper selector and
Settings - Display - Wallpaper - Lock screen

Change-Id: I2e4722d1a6d4ba80a3c656306ceb251d630a8e21

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

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