Add "show all notifications" navbar button

Change-Id: Id591aa98d462b0aa6d6e146d35d6be06608e7ac1
Lockscreen Notifications: dismiss all button, improve animations, cleanup

Change-Id: I408b69a39d9551d00ebc8aa54fb4ef7377fe818b
Lockscreen Notifications: fix show/hide of show all button

& fix endless SystemUI FC when SystemUI is killed

Change-Id: Ie46ef525f72b7ce575dacfb1f05e46a140c87cc5
Lockscreen Notifications: fix NPE