knowledge: temporary knowledge creation removal
knowledge: temporary knowledge creation removal

* Relaxes constrictions on dynamic search function that forced us to
  create temporary knowledge. (closes #698)

Signed-off-by: Leonardo Rossi <5460ec99b71a72e7693c4088b5c2585e76e1c857@cern.ch>

tiborsimko/invenio,inveniosoftware/invenio,tiborsimko/invenio,inveniosoftware/invenio