Advanced low battery indicator options (1/2)

Based on a idea I saw on RootBox and from CR3C0 (thanks guys) which we
modified to an extended version

This commit introduces following new modes to indicate low battery

     * 0 = show dialog + play sound (default)
     * 1 = fire notification + play sound
     * 2 = show dialog only
     * 3 = fire notification only
     * 4 = play sound only
     * 5 = none

Notification behaviour is the same as Pop-up. User can dismiss it manually or it is
dismissed automatically if charger is connected, click on notification opens
PowerUsageSummary. Also you get a status bar ticker message about the notification
and notification is always on first place of list. And last if vibration is enabled
notification vibrates.

Patchsets:
 - codestyle corrections

Patchst
 - add PowerUsageSummary intent

cheers

Change-Id: I84476626b0ff5424454a1132ea4ef77a696070c1