sound settings:
- allow volumes to be unlinked.
- make the volume overlay more functional

Change-Id: Ic5b78b89fcde9420b45fa13b83f1d0f65f9b69ff
Merge branch 'sm-kk-mr1' of https://github.com/SaberMod/android_packages_apps_Settings into sm-kk-mr1

Change-Id: Ifa4781cfcc55da922b89ae2117bf5174e8c8b0c6