serve internet explorer js files too

data/web/inc/header.inc.php

@@ -6,8 +6,8 @@
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>mailcow UI</title>
 <!--[if lt IE 9]>
-  <script src="https://cdnjs.cloudflare.com/ajax/libs/html5shiv/3.7.3/html5shiv.min.js" integrity="sha256-3Jy/GbSLrg0o9y5Z5n1uw0qxZECH7C6OQpVBgNFYa0g=" crossorigin="anonymous"></script>
-  <script src="https://cdnjs.cloudflare.com/ajax/libs/respond.js/1.4.2/respond.min.js" integrity="sha256-g6iAfvZp+nDQ2TdTR/VVKJf3bGro4ub5fvWSWVRi2NE=" crossorigin="anonymous"></script>
+  <script src="/js/html5shiv.min.js"></script>
+  <script src="/js/respond.min.js"></script>
 <![endif]-->
 <script src="/js/jquery-1.12.4.min.js"></script>
 <?php if (strtolower(trim($DEFAULT_THEME)) != "lumen"): ?>