Convert all CoffeeScript to Javascript. See:

http://meta.discourse.org/t/is-it-better-for-discourse-to-use-javascript-or-coffeescript/3153

app/assets/javascripts/admin/routes/admin_customize_route.js

@@ -0,0 +1,9 @@
+(function() {
+
+  Discourse.AdminCustomizeRoute = Discourse.Route.extend({
+    model: function() {
+      return Discourse.SiteCustomization.findAll();
+    }
+  });
+
+}).call(this);