Ticket_544: removal of self-citations

In order to get the correct value for the tori index, self-citations are removed. This is why the field "rn_citation_data" was introduced in the 'metrics_data' collection, which keeps the correspondence between bibcode and reference-normalized citation count for that bibcode. After removing all bibcodes from "rn_citation_data" that are in the submitted publication list, the reference-normalized citation counts are summed for the remaining papers for the tori calculation.