Add LegacyAbstract.contribution relationship
Add LegacyAbstract.contribution relationship

OmeGak/indico,indico/indico,mic4ael/indico,ThiefMaster/indico,DirkHoffmann/indico,DirkHoffmann/indico,OmeGak/indico,mvidalgarcia/indico,mic4ael/indico,mvidalgarcia/indico,indico/indico,indico/indico,pferreir/indico,ThiefMaster/indico,OmeGak/indico,OmeGak/indico,pferreir/indico,mic4ael/indico,indico/indico,ThiefMaster/indico,DirkHoffmann/indico,pferreir/indico,mvidalgarcia/indico,ThiefMaster/indico,DirkHoffmann/indico,mvidalgarcia/indico,pferreir/indico,mic4ael/indico