title: AngularJS ng-value boolean validation
body: <p>To be specific: I have two radio buttons and their ng-model value must be boolean. Since this is not possible with normal html value property I found useful Angularjs ng-value. Problem is when I want to do some validation, when radio button ng-value="false" is selected it recognizes it as an empty ng-model and we have validation error.</p>
  
  <p><strong>Example</strong>: <a href="http://plnkr.co/edit/lvdNHZoSSN1nM6uLyc0Q?p=preview" rel="nofollow">http://plnkr.co/edit/lvdNHZoSSN1nM6uLyc0Q?p=preview</a></p>
  
  <p>Any clue how to tackle this?</p>