Add gesture based lockscreen security. [2/2]

PS2:
Tidy things up a bit.

Change-Id: I83e3ab643e19b2a2d9c8416f4925bbab05bbc896

Conflicts:
	src/com/android/settings/ChooseLockGeneric.java
Fix NPE in Privacy Guard Manager

On tablets such as manta a NPE occurs.  To reproduce go into PGM, press
the back button one time, then go back into PGM.

Remove privacy guard fragment in onDestroyView

Change-Id: I61cebe273fa6fd514f18c86894acd176701148f6

Check if fragment transaction is empty before attempting to remove it

Change-Id: I08591c89559d33fee30ac2934fdbcc30637147da

PrivacyGuard fragment fix - change from empty check to isDestroyed check

Change-Id: I52fe44b7446cd16793df6ac9cdbe31e2ddd70210
Signed-off-by: Paul Beeler <sparksco@gmail.com>

Conflicts:
	src/com/android/settings/liquid/privacyguard/PrivacyGuardManager.java