Fix Albunack to select correct musicbrainz label when multiple labels with same name

This website pre-selects entities without checking if they are correct. It takes the first result, even if the text does not match, and ignores existing MB-Discogs links.

Here is an example:
http://www.discogs.com/release/3256085
http://albunack.net/addrelease/?discogsid=3256085&artistid=3be4099e-f180-4038-af84-ae18a09eab02

The wrong label entity gets preselected.

The website serves no purpose when https://github.com/murdos/musicbrainz-userscripts does the same thing, but correctly.
I suppose blocking the referrer and providing an explanation should be enough.