Merge pull request #7486 from evilhamster/addartistdescfield

[music] Change the way the (album)artists tag are handled

diff --cc xbmc/music/Album.cpp
Simple merge

diff --cc xbmc/music/Album.h
Simple merge

diff --cc xbmc/music/MusicDatabase.cpp
Simple merge

diff --cc xbmc/music/tags/MusicInfoTag.cpp
Simple merge