SystemUI: statusbar: Fix QS quick pulldown feature

Bring in the fixes from CM 13.

This commit squashes the following patches from CM 13.0:
68c40f32 SystemUI: fix QS quick pull down
477f58dc SystemUI: hook up settings observer in notificationpanel
d2bec52c SystemUI: Fix quick-quick settings pulldown settings
eb10bc20 Add left QS quick pulldown (1/3)

Change-Id: Ie122477261d96499c80640cf274d22fba6642a01