framework: Battery bar (1/2)

Patch Set 1:    * initial release
Patch Set 2:    * minor code cleanup

SCREENSHOT: http://i.imgur.com/JSnr5tn.png

Change-Id: I4f0d65a4b9673a63ed44a32619c1dba882f5e9ea

Conflicts:

	packages/SystemUI/res/layout/status_bar.xml
	packages/SystemUI/res/values/attrs.xml