title: Yii 2 Optional Parameter
body: <p>Ok, I am transitioning an app from yii 1.1 to yii 2, unfortunately I cannot figure out how to use optional parameters within my url routes.  Even when I set defaults in the urlmanager in config I can't state the second parameter without the first one or I end up with a 404 error. </p>
  
  <p>Is there a way to replicate optional url parameter rules such as </p>
  
  <pre><code>array( '&lt;controller:\w+&gt;/&lt;action:\w+&gt;?(/&lt;status&gt;)?',
  'pattern' =&gt; '&lt;controller&gt;/&lt;action&gt;'                   
  ),
  </code></pre>
  
  <p>in yii 2 ?</p>