updated talk and task detailed view, when not found show 404
updated talk and task detailed view, when not found show 404

cateee/fosdem-volunteers,jrial/fosdem-volunteers,FOSDEM/volunteers,jrial/fosdem-volunteers,FOSDEM/volunteers,cateee/fosdem-volunteers,jrial/fosdem-volunteers,cateee/fosdem-volunteers,jrial/fosdem-volunteers,FOSDEM/volunteers,cateee/fosdem-volunteers,FOSDEM/volunteers