Settings: Security: implement a pin keypad shuffler [2/2]

this is to further prevent people using the tablet guessing your pin based on fingerprints left on the screen
example of the expected outcome - https://www.dropbox.com/sh/r3xb2q53ksaqni9/Oz1Eu8Dm7O

PatchSet:
- fix checkbox was wrong assigned
- enable only for PIN Password lock
- small cleanup of old code

PatchSet:
- cleanup

PatchSet:
- add modes.....disabled/always/on request

Change-Id: I7e485827f6d62ee239015cfa96f2a20169d28486

Conflicts:

	res/values/slim_arrays.xml
	res/values/slim_strings.xml
	src/com/android/settings/SecuritySettings.java