403: redirect user to login page if not logged in

Signed-Off-By: Pedro Ferreira <pedro.ferreira@cern.ch>

lib/response.js

@@ -17,7 +17,13 @@ var utils = require('./utils')
 // public
 var response = {
   errorForbidden: function (res) {
+    const {req} = res
+    if (req.user) {
       responseError(res, '403', 'Forbidden', 'oh no.')
+    } else {
+      req.flash('error', 'You are not allowed to access this page. Maybe try logging in?')
+      res.redirect(config.serverURL)
+    }
   },
   errorNotFound: function (res) {
     responseError(res, '404', 'Not Found', 'oops.')