title: How can I get viewModel object in store filter function?
body: <p>I defined the store and a filter. The ViewModel contains <code>test</code> object I need to filter store items by this object.</p>
  
  <pre><code>Ext.define('XXX.view.XXX.ViewXXXXModel', {
      extend: 'Ext.app.ViewModel',
  </code></pre>
  
  <p>...</p>
  
  <pre><code>    stores: {
          agreements: {
              source: 'XXX',
              filters: {
                  filterFn: function(item) {
                      return item.some_field !== this.get('test').somevalue;
                  }
              }
          }
      }
  </code></pre>
  
  <p>I cannot access the test object of View Model from filter function?</p>