Hide Superuser entry if root access for apps is disabled.

Change-Id: Ibb77ba5a0fccf22564a26b8b1e13f7762c65718e

Conflicts:
	src/com/android/settings/Settings.java
Fix scrollbars appearing out of place in Superuser.

Change-Id: Ia206623716192e479901c02cf94de84a29e0479e