return a 404 if a request tries to fetch a dir
return a 404 if a request tries to fetch a dir

scorphus/thumbor,voxmedia/thumbor,thumbor/thumbor,kkopachev/thumbor,scorphus/thumbor,scorphus/thumbor,gi11es/thumbor,okor/thumbor,thumbor/thumbor,okor/thumbor,thumbor/thumbor,gi11es/thumbor,okor/thumbor,voxmedia/thumbor,marcelometal/thumbor,thumbor/thumbor,marcelometal/thumbor,marcelometal/thumbor,scorphus/thumbor,voxmedia/thumbor,kkopachev/thumbor,kkopachev/thumbor,gi11es/thumbor,kkopachev/thumbor