LN: Some fixes & cleanup

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

Change-Id: I87db92a7ee4eb9329ec1ec69008e612a619d5c91

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

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