Option to use volume keys to control media volume anytime (1/2)

Some users don't adjust ringtone volume often (e.g. only use toggle to
switch between silent and non-silent) mode. Having an option to
use the volume keys to control media volume anytime allows media
volume to be controllled/muted before entering a game or other apps
with sound in an undesirable location.

Change-Id: I6dbd25d1a14bcf5b1bf0b0468b96f4b4f8efdb14
Settings: Add missing AF translations

Change-Id: I973d14e63b00d35332dea76ae18af5db11d7e66a
Settings: added contact icon + label + German translation

Change-Id: Id1f5a6f632f0ed4e93901c32bf09784b8d8261b0