QuickSettings : Battery initial status

Battery tile upon being added relies on a battery level changed call
to update its status. Thus if upon adding, the battery level is not changing
or till the period when it updates, the tile shows an unknown state.

This patchset resolves this issue by making the controller store its last received value
and distributing it to the tiles when they register for changes.

https://jira.cyanogenmod.org/browse/CYAN-1374

Change-Id: Ia2e887e545430ed02c179a3c8f4b7e269a4817c8
Merge branch 'cm-10.1' into martincz