title: injecting ServiceLocator via ServiceLocatorAwareInterface doesnt work
body: <p>i read that implementing: ServiceLocatorAwareInterface will inject the serviceLocator to the same class. 
  So I got this:</p>
  
  <pre><code>Class MyModel implements ServiceLocatorAwareInterface {
  
  
      protected $serviceLocator;
  
  
      public function setServiceLocator(ServiceLocatorInterface $serviceLocator)
      {
          $this-&gt;serviceLocator = $serviceLocator;
      }
  
  
      public function getServiceLocator()
      {
          return $this-&gt;serviceLocator;
      }
  </code></pre>
  
  <p>}</p>
  
  <p>But  $this->serviceLocator is always NULL</p>
  
  <p>Do i have to do more than that?</p>