title: How do we query nested dictionary in django-hstore?
body: <p>I have this stored in my <code>serializedDictionaryField</code>:</p>
  
  <pre><code>data = {
      'k1': 'v1',
      'k2': 'v2',
      'k3': {'nested_k': 'nested_v'}
  }
  </code></pre>
  
  <p>Is it possible to filter by values of nested dictionary? something like</p>
  
  <pre><code>Model.objects.filter(data__contains={'nested_k': 'nested_v'})
  </code></pre>