fix wrong arguments passed to tornado.web.StaticFileHandler

main.py

@@ -180,7 +180,7 @@ def main():
   application = tornado.web.Application([
     (r"/", IndexHandler),
     (r"/" + SCRIPT_PATH, ToolHandler),
-    (r"/([a-fA-F0-9]{2}/[a-fA-F0-9]{38})(\.\w*)?", tornado.web.StaticFileHandler, {
+    (r"/([a-fA-F0-9]{2}/[a-fA-F0-9]{38})(?:\.\w*)?", tornado.web.StaticFileHandler, {
       'path': options.datadir,
     }),
     (r"/([a-fA-F0-9/]+(?:\.\w*)?)", HashHandler),