using req.hostname instead of deprecated req.host

pass/app/Langdetector.js

@@ -3,7 +3,7 @@ module.exports = {
     lookup: (req, res, options) => {
         let language = 'de';
 
-        if (req.host === "metager.org") {
+        if (req.hostname === "metager.org") {
             language = 'en';
         }