Simple catch-all route for 404s on pages

ui/app/router.js

@@ -35,6 +35,8 @@ Router.map(function() {
   if (config.environment === 'development') {
     this.route('freestyle');
   }
+
+  this.route('not-found', { path: '/*' });
 });
 
 export default Router;

ui/app/routes/not-found.js

@@ -0,0 +1,11 @@
+import Ember from 'ember';
+
+const { Route, Error: EmberError } = Ember;
+
+export default Route.extend({
+  model() {
+    const err = new EmberError('Page not found');
+    err.code = '404';
+    this.controllerFor('application').set('error', err);
+  },
+});