Websearch: include 'cc' in RSS <channel>'s <link>

* If the 'cc' collection is defined when producing the RSS feed then
  it's included in the <link> tag under the <channel> tag.
  (closes #2013) (closes #2014)

Signed-off-by: Nikolaos Kasioumis <nikolaos.kasioumis@cern.ch>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>