HeadsUp: Launch in floating window

Add some part of NotificationHelper
Credits to AOSPA team

Change-Id: I7001cebd69790b46b8dcfe9150c7ef104e5427a2
frameworks: Fix blacklist in floating notification launch with expanded desktop on

Change-Id: Ifa254dc78c41a1353b429f3ba7b6478979459ccf

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
Frameworks: Add background to halo button
Floating window: Fix possible NPE

Avoid possible NPE if app provides no interface such as pushbullet's
test notification & other apps which provide one.

Change-Id: I35c13959296a56e44f21f1aee0a736e7f786aa57

Conflicts:
	packages/SystemUI/res/values/cm_strings.xml