WebSearch: better I18N handling of RSS feeds
WebSearch: better I18N handling of RSS feeds

* Consider 'ln' parameter when displaying RSS feed.

* Added CFG_WEBSEARCH_RSS_I18N_COLLECTIONS to configure collections
  that should add 'ln' parameter to the RSS feed on their main
  webcoll-generated search interface page.

* Also consider user_info when formatting RSS, mainly so that
  BFE_* can access user_info['uri'] if needed.

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