title: radioButtonList checked by default
body: <p>I created a option list with 2 options: Yes and No like below</p>
  
  <pre><code>&lt;?php echo $form-&gt;radioButtonList($model,'active', array(1=&gt;'Yes', 0=&gt;'No'), array('separator'=&gt;"" )); ?&gt;
  </code></pre>
  
  <p>How can I set option 1 to be selected by default ?</p>