Lockscreen Notifications: Privacy mode

Hide notifications content on secure lockscreen.

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

Change-Id: I714e29ef7b41b6764c1ddcb9c52303b7707c90fb

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