records: API for database querying with DOI
records: API for database querying with DOI

* Adds API to query the database with a DOI.

Signed-off-by: Pedro Gaudêncio <4ac9fc3191981fa13218c244381da17a72546105@cern.ch>
Reviewed-by: Javier Martin Montull <ea6b80e26c65acc242d8916fb6eefa01b123cb69@cern.ch>
Reviewed-by: Jiri Kuncar <2bdffcb416fed3002465740d19a053a39918cbe5@cern.ch>

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