Remove useless __str__ methods
Remove useless __str__ methods

Those objects have a much more useful __repr__

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