Quick Settings: Add visual indicator of ON/OFF Setting of Mobile Data tile

This addresses issue CYAN-221

Change-Id: I7dc0c8943df7a9478655bdde6745662c3831288f
QuickSettings: Better Mobile network tile disabled overlay handling

Change-Id: I0a2b6b570912002d9f1edf5809c1aa532e1531a0
SystemUI: allow update Mobile Network Type tile display

For the moment, this tile is only updated when clicking on it.
With these changes we have the same behavior as the other tiles:
if setting is changed in system settings, Mobile Network Type tile
display is updated.

    * Patch Set 1: Initial commit
    * Patch Set 2: Some corrections, commit message changed

Change-Id: I6cadadf4b9e3c9f478a4286e26d657da4f3ff015