Framework: Add missing part of 'Lock before unlock'

Keyguard: Turn lock-before-unlock into a user-configurable setting

Showing the unsecured lock screen (Slider/widget screen) before the
security screen is now a secure Setting (still defaulting to off)

Change-Id: I0a11f82ffe074d289129b2b972ffc0135eea81ed

Other parts were merged already