title: Load TreeStore at once. Extjs 4
body: <p>My question is: How can I load the TreeStore at once? 
  Because right now, if I'm using proxy, to get Tree after rendering, when I expand the leaf, there is one more request with GET parameter <code>'node'</code> - the id of leaf node. So I need to response with the tree of this leaf. but I want to load ALL tree at once and no more requests for that tree.</p>
  
  <p>Right now I have below code:</p>
  
  <pre><code>    Ext.define('AdminPanel.TreeNavigation', {              
          extend: 'Ext.data.Model',  
          fields: ['id', 'text', 'leaf', 'children']  
      });
  
  
      var store = Ext.create('Ext.data.TreeStore', {
  
                      model: 'AdminPanel.TreeNavigation',  
  
                      proxy: {  
                          type: 'ajax',
                          url : 'admin/getTreeNav',
                          reader: {
                              type: 'json',
                              root: 'result'
                          }
                      },
  
                      root: {
                          expanded: true
                      }
  
                  });
  </code></pre>