更新前端静态网页获取方式，放弃使用后端获取api

frontend/node_modules/websocket-extensions/LICENSE.md

@@ -0,0 +1,12 @@
+Copyright 2014-2020 James Coglan
+
+Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+this file except in compliance with the License. You may obtain a copy of the
+License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software distributed
+under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+CONDITIONS OF ANY KIND, either express or implied. See the License for the
+specific language governing permissions and limitations under the License.