SystemUI: Add dock battery icon styles

Support for dock battery icon styles. This changes does a refactor of DockBatteryController to
extend BatteryController and create a new CircleDockBattery that extends CircleBattery (that listen
for dock battery events)

Patchset 2: Fully functional.
Patchset 3: Fixed min icons. Rebased.
Patchset 4: Create full device specific service in frameworks
            Move dock battery stuff from the framework to a device handler.
            Register/unregister DockBatteryController receivers
            Remove battery views if device doesn't support dock battery
            Refresh status on dock and screen on events
            Rebased
Patchset 5: Transformers backwards compatibility
            Better main battery status detection (use status instead of plugged type)
            Fixed battery cluster space in status bar
            Rebased
Patchset 6: Fix dock icons in ligths out mode
Patchset 7: Fix code style
            Fix lockscreen status
            Fix lights out mode (typo)
            Fix images size
            Rebased
Patchset 8: Fix icon images
            Fix status on full charge
            Rebased

TF700T implementation: http://review.cyanogenmod.org/#/c/31298/

Change-Id: I9a576d1b279f1883f736ac3bcd2435c4b95a73de
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>