Fix up the QS gutter

 - Don't show when collapsed, show divider instead
 - Don't show when no notifications
 - Animate between states while expanding/collapsing
 - Other visual cleanup

Test: visual
Change-Id: I923c963fa70d63601b6a181299b04c5fc49922bb
Fixes: 38199857
Fixes: 38483355
Fixes: 38409326
Fixes: 38417776
(cherry picked from commit 4de5d3c0)