Settings: add user configurable lockscreen shortcuts (2/2)

Change-Id: I6333792830f7357a9f4fcd5d42c479ec60a71915
Merge remote-tracking branch 'upstream/lp5.0-caf' into lp5.0-caf
Merge branch 'lp5.0-caf' of https://github.com/Validus-Shamu/packages_apps_Settings into lp5.0-caf