HALO: batch message icon for hdpi and mdpi

It's hard to keep up with Paul hehe

Conflicts:
	packages/SystemUI/res/drawable-hdpi/halo_batch_message.png
	packages/SystemUI/res/drawable-mdpi/halo_batch_message.png

Change-Id: Ifbb2995da0b365a3298ec74576338b82747f054b