Remove unnecessary debug print
Lookup's start_new_thread should also be inside try-catch
Find path in libmediaart response by searching for path

It seems that since libmeddiart 0.6 params are swapped,
 we should not rely on indexes and search for path instead

https://bugzilla.gnome.org/show_bug.cgi?id=737571
Set grilo plugin ranks to avoid extra last.fm calls

https://bugzilla.gnome.org/show_bug.cgi?id=736241