hide graph when no proto (#105)

visualdl/server/visualDL

@@ -195,6 +195,7 @@ if __name__ == '__main__':
         logger.error("should pass in logdir option")
         sys.exit(-1)
 
+    if options.model_pb:
         # draw graph
         image_dir = os.path.join(options.logdir, "graphs")
         if not os.path.isdir(image_dir):