HeadsUp: basic Headsup implementation (2/2)

  -enables the HeadsUp notification feature
  -add a HeadsUp qs tile, tile long press will open the do not disturb settings
Ethernet: observe the ethernet on/off state (2/2)

  observe when the qs tile turns ethernet on or off, write it to a Settings.System setting
  allows Settings switch to stay in sync with the tile

Conflicts:
	src/com/android/settings/ethernet/EthernetEnabler.java
HeadsUp: option to show at the bottom of the screen (2/2)