LN: Some fixes & cleanup

- Fix bug that the notification is launched when a button on it is pressed
- Show new notifications first

Conflicts:
	packages/Keyguard/src/com/android/keyguard/NotificationHostView.java

Change-Id: Ideb683f1788cf3188ac23a326193e199f16052e5

Conflicts:
	packages/Keyguard/src/com/android/keyguard/NotificationHostView.java