HOVER: Options to exclude non-clearable and low priority notifications [1/2]

Change-Id: I0563a5a05f697202d11343451c481d8a150717d5
Master switch to disable Hover [1/2]

Change-Id: I928bf5c42fb4a33109198475cc136bd86f11056d

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