WebJournal: Indico seminars widget improvement

* Improves the Indico seminars widget but fetching more carefully
  information about the creator/chair of the event as well as the
  URL.  (closes #1980) (closes #1981)

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