deposit: addition of api for crossref doi fetch

* This searches the DOI on crossref and returns
  the result as JSON format, also handles if the
  DOI isn't found or it's malformed.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>
deposit: addition of block tags to template

* Adds block tags to run_base.html template
  to improve costumization

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>