Add slightly better event date validation
Add slightly better event date validation

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