legacy: WebSubmit removal
legacy: WebSubmit removal

* INCOMPATIBLE Removes legacy WebSubmit together with file convertors.
  (addresses #3233)

Signed-off-by: Jiri Kuncar <2bdffcb416fed3002465740d19a053a39918cbe5@cern.ch>

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