Fix ProposalGroupProxy __eq__
Fix ProposalGroupProxy __eq__

We want the proxy to be considered equal to its associated object

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