title: How to configure Id property of Restangular URL building
body: <p><strong>Let</strong>,</p>
  
  <pre><code>Restangular.one('users').getList().then(function(users) {
    $scope.user = users[0]; 
  });
  </code></pre>
  
  <hr>
  
  <p><strong>Another GET request:</strong></p>
  
  <p>Let:    <code>user: { id: '123' }</code></p>
  
  <p><code>$scope.cars = $scope.user.getList('cars');</code>   This would fires a GET request: /users/<strong>123</strong>/cars</p>
  
  <p>where the <strong>123</strong> is gotten from the <em>id property</em>.</p>
  
  <hr>
  
  <p><strong>Question:</strong></p>
  
  <p>Is it possible to explicitely configure if my object's <em>id property</em>, for example: was named <strong>username</strong>.</p>
  
  <pre><code>user: { username: '123' }
  </code></pre>