Master switch to disable Hover [1/2]

Change-Id: I928bf5c42fb4a33109198475cc136bd86f11056d

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
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