formatter: output format 'recjson' addition

(addresses #1908)

Signed-off-by: Eirini Psallida <eirini.psallida@cern.ch>
`depends_on = ['invenio_2014_08_12_format_code_varchar20.py']`

--
see 37d44cb559be43108e095a49230923213fd62eac