FaceUnlock: Check if faceunlock is disabled

JIRA: CYAN-3622
Issue: https://jira.cyanogenmod.org/browse/CYAN-3622

Change-Id: Iaf656f1aecb72610a46183294de25151e8df4b05
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Merge "FaceUnlock: Check if faceunlock is disabled" into du44