message: fix 404 handling in fastboot
  Because apparently the xhr implementation there has different errors, and this is why we can't have nice things.
diff: @@ -45,5 +45,7 @@ export default Ember.Route.extend({
  function is404(err) {
  - return err.isAdapterError && err.errors && err.errors.length > 0 && err.errors[0].code === 404;
  + return err.isAdapterError && err.errors && err.errors.length > 0 && (
  + err.errors[0].code === 404 || err.errors[0].status === "404"
  + );
  }
  