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.

Change-Id: I54141cbfc91d08c28ef524f4155b673ae8dee90e
Separate Android Encryption Password from Lockscreen Password

This permits the use of a different (hopefully longer and more complex!) encryption
password, while using a simpler (and easier to type) lockscreen password.

Change-Id: Ib8c62c8eb4c86cd9e0117444231e8139c08ad1b6

Conflicts:
	res/values/custom_strings.xml