records: return cleaned record json
records: return cleaned record json

* NOTE `get_unique_record_json` returns cleaned data by
  `Record.dumps(clean=True)`.

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

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