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
Revert "Settings: Don't crash if we pause too quickly"

This reverts commit 58e8049e1ca6889cd4e9f0b00aec83d59f18afed.

Change-Id: Ibd07c77c10eb98e9c1d2dc09a8fb0841bdc1caa6