[3/3] Settings: Audio Themes Support
from: https://gerrit.omnirom.org/#/c/5245/

PS 2&3: Update author
PS4: Rebased & fix spaces
Ps5: Move the preference under System sound header

change-Id: I6a92e4c9173be6f6ce31e8555902ea36e05bb82f

Conflicts:
	res/values/dcm_strings.xml