title: checked for angularjs not working properly for radio type input field
body: <p>I have a simple form for gathering text and choice data like -</p>
  
  <p><strong>HTML</strong> Form -</p>
  
  <pre><code>&lt;div class="form-group"&gt;
      &lt;label class="col-sm-2 control-label"&gt;Event Name&lt;span class="asterisk"&gt;*&lt;/span&gt;&lt;/label&gt;
      &lt;div class="col-sm-1"&gt;
          &lt;input type="text" placeholder="Music Concert at Las Vegas" ng-model="event.name" required="required" class="form-control"&gt;
      &lt;/div&gt;
  &lt;/div&gt;    
  &lt;div class="form-group"&gt;
      &lt;label class="col-sm-2 control-label"&gt;Is Active&lt;span class="asterisk"&gt;*&lt;/span&gt;&lt;/label&gt;
      &lt;div class="col-sm-1"&gt;
          &lt;input type="radio" name="is_active" ng-model="event.is_active" value="yes" checked="checked" class="form-control"&gt;&amp;nbsp;&amp;nbsp;Yes
      &lt;/div&gt;
      &lt;div class="col-sm-3"&gt;
          &lt;input type="radio" name="is_active" ng-model="event.is_active" value="no" class="form-control"&gt;&amp;nbsp;&amp;nbsp;No
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>And in my <strong>controller</strong> -</p>
  
  <pre><code>$scope.event.is_active = "yes";
  </code></pre>
  
  <p>Now the problem I am facing is -</p>
  
  <ol>
  <li>If I remove the <code>$scope.event.is_active = "yes"</code> from the controller "Yes" option should remain works due to the presence of <code>checked="checked"</code> HTML attribute set, but it won't.</li>
  <li>Now If I remove the <code>checked="checked"</code> attribute so whether do I have <code>$scope.event.is_active = "yes"</code> in my controller or not it won't work i.e not of the option is pre checked.</li>
  </ol>
  
  <p>Let me know what I am missing with here with the angular way.</p>