20130301 - better MusicBrainz Disc ID support

[Dan Gravell]

I've deployed a new beta with a significant reworking of how results are looked up, only applied to MusicBrainz Disc ID queries for now.

Before, a query for a MusicBrainz Disc ID would only lookup artwork on MusicBrainz. As only 9% (ish) of MusicBrainz releases have cover art, the likelihood of a match was poor.

This has been changed to re-use what data *has* been discovered on MusicBrainz to query other sources. For instance, if a barcode is in the MusicBrainz database, this is used to lookup the cover art on Discogs.

This results in a huge increase in the amount of art matched by MusicBrainz Disc ID. Try it out:

http://onemusicapi-beta.elasticbeanstalk.com/20130130/release?musicBrainzDiscId=22ZZjw1vdPPqOnWbkExCY6S3EX0-&inc=images

This is a new server just for beta releases. I will disable it a short period after the beta has been released, so don't rely on it! Note you don't require your user_key for this server, but you can specify it if you like.

I hope to add the same approach to the Acoustid fingerprint queries soon. Again, these suffer from only returning cover art from MusicBrainz right now.

IT WOULD HELP ENORMOUSLY if all testers could keep a record of the disc IDs they use to query OMA, and then report these disc IDs in any feedback. 

Dan