WebSearch: fixed OpenSearch markup in RSS feed
WebSearch: fixed OpenSearch markup in RSS feed

* Fixed link to OpenSearch description.
* Correctly included <itemsPerPage> element (instead of repeating <totalResults>).
* Partially fixes #107.

tiborsimko/invenio-records,inveniosoftware/invenio-search,tiborsimko/invenio-search,tiborsimko/invenio-search,inveniosoftware/invenio-search,inveniosoftware/invenio-records,tiborsimko/invenio-records,inveniosoftware/invenio-records