profiles: Add support for disabling screen lock

 * We can now have the option of disabling lockscreen security as part
   of the profile. A good use case for this is to create "Car" profile.
   You certainly don't want to input a pattern, or worse, face-unlock if
   you should happen to break the law and use your phone whilst driving.
 * Profile system now permits insecure mode or entirely disabling
   lockscreen as an override.
 * Fix issue where changes aren't applied if the active profile is
   modified.
 * Also fix a couple of string-comparison derps.

Change-Id: I07a09b7011bad4f32cdd7bfa576e3befa71193ea