20150319 - latest Discogs image API change

[Dan Gravell]

A number of changes in this beta...

- Internal support for the new approach to Discogs image download. No client changes required

- Performance improvements with more aggressive caching of internal data

- When scoring artist names, ignore Discogs' disambiguation parentheses

- Improved Acoustid matching algorithm

- Include position for media items in disc/associated_releases

- Drop some results using CloudSearch text_relevance

No API changes, so the API can be reached on our beta server at http://onemusicapi-beta.elasticbeanstalk.com/20140925/

Dan