Add copyright header on website files

website/server/server.js

@@ -1,3 +1,12 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
 "use strict";
 var connect = require('connect');
 var http = require('http');