Remove unused route from the homepage

The new homepage is now only served at '/'.
'/new-homepage' was a temporary route only used during development.

h/static/scripts/site.js

@@ -21,7 +21,7 @@ document.addEventListener('DOMContentLoaded', function () {
 
   // setup route
   var route = document.location.pathname;
-  if (route.match('^/(new-homepage)?$')) {
+  if (route === '/') {
     new InstallerController(document.body);
   } else if (route.match('^/groups') === 0) {
     setupGroupsController(route);