HOVER: Option to disable HOVER-Button in StatusBar [1/2]

If the button is hidden, user can activate Hover in the Settings instead

Change-Id: I76e99da7a83b6a5dd35c2965b311009dfc819085

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java

 Author:    Schubi <schubi@erlangen.ccc.de>