[grilo-plugins] (4 commits) Non-fast-forward update to branch wip/jfelder/theaudiodb-artist-art

[Jean Felder <jfelder src gnome org>]

The branch 'wip/jfelder/theaudiodb-artist-art' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  092d9b7... theaudiodb: Use the correct variable for album
  a512cd5... theaudiobd: Add support for artist art

Commits added to the branch:

  16e815b... tracker: Use the correct property to retrieve album title (*)
  3d8839b... theaudiodb: Add a unit test
  d222b2d... theaudiodb: Use the correct variable for album
  b96acaf... theaudiobd: Add support for artist art

(*) This commit already existed in another branch; no separate mail sent