Option to disable safe volume warning [2/2]

* This message appears when using headphones and listening to music
* This setting will be applied at boot, so a reboot is necessary

Change-Id: I2cdee8def41105df9266126d694cfd6c22ef4461

Conflicts:

	res/values/custom_strings.xml
	src/org/omnirom/omnigears/ButtonSettings.java