Settings: Don't crash if we pause too quickly

Notifier is unregistered in every case in pause.
However, if you close the Settings app too quick, the notifier
might not be registered at all, causing an IllegalArgumentException
during the unregistering.

Conflicts:
	src/com/android/settings/Settings.java

Change-Id: I9cd8934c3dd208cc6d78143de5d1457995e06c5c
Merge pull request #14 from LiquidSmooth/kitkat3

Settings: Don't crash if we pause too quickly