add apache license

public/content-script.js

@@ -1,3 +1,24 @@
+/**
+* Licensed to the Apache Software Foundation (ASF) under one
+* or more contributor license agreements.  See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership.  The ASF licenses this file
+* to you 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.    
+*/
+
+
+
 /*global chrome*/
 chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
   sendMessageToPage(request);
@@ -108,4 +129,4 @@ if (account !== null){
   account.addEventListener('click', function() {
     chrome.runtime.sendMessage({ action: 'showExtension' });
   });
-}
+}