Lockscreen Notifications: rewrite add notification logic

There were some problems with notifications getting replaced while the user was currently dragging them.
This commit should fix that by always waiting until animations and user input are finished before replacing a notification view.

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

Change-Id: I2dc8b1d84512ce2217be62655e10c766c14d7d10

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