Changed contextual notification panel headers images/ clean up

See images - http://i.imgur.com/PupEJ5p.jpg

Change-Id: If848d162523610946c317919d2f6664d891906e6

Conflicts:
	packages/SystemUI/res/drawable-xhdpi/notifhead_afternoon.jpg
	packages/SystemUI/res/drawable-xhdpi/notifhead_morning.jpg
	packages/SystemUI/res/drawable-xhdpi/notifhead_night.jpg