SystemUI: toggle enhancements

Provide a default icon with each toggle
so that ROM Control can query these drawables
and display them to be prettier!

Change-Id: I9fe0b860dd7d9b7d8ce8fc5d1dcfa9186f809fb0
Signed-off-by: Roman Birg <romanbirg@gmail.com>

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