Fix issues #16941902, #16901402, and #16135174.

Issue #16941902: Charged % of battery is mismatching between phone status
area(top right corner) and battery screen

Need to make sure the stats are updated when we come back to
the foreground.

Issue #16901402: Crash in Settings observed after tap on Battery option

Don't allow us to have a null stats object.

Issue #16135174: Apps page "smoke" gradient footer must be removed

Finish tweaking layout to match mocks.

Change-Id: I29d56b506a9468ec548feef7c3f9502a9b16ef4d