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.

Change-Id: Ieaec759e4378a9a7701e6fba46ed33464caaee0a
TICKET: CYNGNOS-1041