SysUI: Clean up objects when recreating statusbar

Recreating the status bar for theme changes causes several views
and objects to not get GCed.  By analyzing hprof dumps of
com.android.systemui we can identify these issues and get things
properly cleaned up, and that's what this patch is doing.

CYNGNOS-1583

Change-Id: Id958b76a093431854661d147268ddbe260613017