MARC21 feed support

Now you can get MARC21 feeds from OpenSearch, e.g.
http://<host>/opac/extras/opensearch/1.1/-/marc21?searchTerms=piano

with the Concerto dataset.

[LFW] Syntax corrections, utf-8 encoding, release note

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>