title: How not to change url when show 404 error page with ui-router
body: <p>I want to show 404 error page, but also I want to save wrong url in location.</p>
  
  <p>If I'll do something like that:</p>
  
  <pre><code>$urlRouterProvider.otherwise('404');
  $stateProvider
      .state('404', {
          url: '/404',
          template: error404Template
      });
  </code></pre>
  
  <p>url will change to <code>/404</code>. How I can show error message on wrong urls without changing actual url?</p>