Framework: Enable multi-user support for Quiet Hours

Change-Id: Ica967ff6bf5842a08421583449876ba73de13d51
Framework: Fix multi-user support in AudioService

Change-Id: Iddeeeac0734a237103e238bcdaa1e85806a64e4f
SystemUI: Remove the dark pixel artifacts from the back arrow drawable

The arrow had some mostly transparent pixels that made it look
kind of like the device had defective pixels. Found by Cyril Mottier.

Change-Id: Ia78453868ebe7e3291d01c96b9beafc78ea3cdcc

Conflicts:

	packages/SystemUI/res/drawable-xhdpi/ic_sysbar_back_land.png