Add Quick Settings USB Tether tile (2 of 2)

Patch Set 8: Make tile dynamic

- Thanks to Björn Lundén for the drawables

Change-Id: I414848f6cb8a789d0b5edfcb79ab53cb85ebc20e
Allow setting a per-device default configuration for STATUS_BAR_BATTERY

Batteryless devices (like TV-connected mediacenters/STBs) don't need
the battery icon there at all.

Change-Id: Iac7e1b0b813c260bc78f4733409a30da7bda248d