Prefer artist over album artist.

E.g. when playing a compilation title, one very likely wants to see the real
artist instead of 'Various artists'.

Change-Id: Ie200f2f8b0b90d3470c2e2e4ca6f91f9b117fb1f
change default for unknown sources & verify apps

Change-Id: I04467c0c1ef3985b416f6e58013ddc3ce4137712