[1/2] frameworks: bring back the status bar activity indicators for mobile data and wifi

Google were nice enough to create xxhdpi drawables for us before removing them.

Reverts "Remove signal/wifi activity indicator icon overlays."

This reverts commit fcc901c10bffdfb9c6b31e676dec36b47d949979.

Included NetworkController.java modification from Iaaa556ffab3ed4be1da8016ed40d0a9c2efcde01

Adding preference for arrows

PS14: Fixing errors

PS15: Turning arrows off done via actual removing drawables work, so when arrows are turned off,
they do not redraw statusbar anymore :-[

PS16: Commit Iaaa556ffab3ed4be1da8016ed40d0a9c2efcde01 merged to this one

PS17: Rebase to allow merge with latest source

Change-Id: I7aa85f7c8442c45d17e42cac7823dfe93e3f24c1

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/res/layout/signal_cluster_view.xml
	packages/SystemUI/src/com/android/systemui/statusbar/SignalClusterView.java
	packages/SystemUI/src/com/android/systemui/statusbar/policy/NetworkController.java