title: Optional params in angularjs $resouce method
body: <p>my case is, i want angularjs auto remove parameters defined in method :</p>
  
  <p>My definition :</p>
  
  <pre><code>var service = $resource(apiConstant.baseUrl + '/website/:action', {port : ':8080'}, {
          save: {
              method: 'GET',
              isArray: false,
              params: {
                  action: 'save', id: '@id', name: '@name', description: '@description',
                  ownerId: '@ownerId', checked: '@checked'
              }
          }
      });
  </code></pre>
  
  <p>When i call service.save({id :3}), the actual URL generated is :</p>
  
  <pre><code>website/save?checked=undefined&amp;description=undefined&amp;id=3&amp;name=undefined&amp;ownerId=undefined
  </code></pre>
  
  <p>How can i tell angularjs auto remove those parameter not specified ?</p>
  
  <p>I'm just want like this  :</p>
  
  <pre><code>website/save?id=3
  </code></pre>
  
  <p>Thanks.</p>