Feat: Allow users to disable safe headset volume warning (2/2)

Change-Id: I6211b7698ab299c3d77a6a57fb41c296865dce7a
Signed-off-by: Gergely Szell (sethyx) <szell@hu.ibm.com>

Conflicts:
	res/values/strings.xml
	res/xml/sound_settings.xml
	src/com/android/settings/SoundSettings.java