WebSearch: add download graph to record blueprint
WebSearch: add download graph to record blueprint

* Add download graph to template context to match functionality
  of previous Invenio versions.

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

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