MBS-2714 Add support for Series.
https://bitbucket.org/metabrainz/musicbrainz-server/pull-request/952/mbs-7533-allow-creating-a-series-from/diff
https://bitbucket.org/metabrainz/musicbrainz-server/pull-request/952/mbs-7533-allow-creating-a-series-from/diff