Add missing i18n to participation "error" messages
Add missing i18n to participation "error" messages

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