title: Extjs 4.2.1 - config autoLoad:false Fails
body: <p>I define a <code>treepanel</code> extend <code>extend: 'Ext.tree.Panel'</code> and that has initComponent function like </p>
  
  <pre><code> Ext.define('Example', {
      extend: 'Ext.tree.Panel',
      title: 'Example',
      useArrows:false, 
      rootVisible: false,
      border: false,
      initComponent: function () {
          var store = Ext.create('Ext.data.TreeStore', {
              fields: [
                  {name: 'id',     type: 'string'},
                  {name: 'text',     type: 'string'}
              ],
              autoLoad : false, // not working
              proxy: {
                  type: 'ajax',
                  url: 'data.php',
                  reader: {
                      type: 'json',
                      root: 'results'     
                  }
              }
  
          });
          this.store = store;
          this.callParent(arguments);
      }
   });
  </code></pre>
  
  <p>I try to set <code>autoLoad: false</code> but that always loading when i create my <code>treepanel</code></p>
  
  <p>When i try to config below code to store then <code>autoLoad: false</code> working but my <code>treepanel</code> after load is blank</p>
  
  <pre><code>                root: {
                      text: 'Ext JS',
                      id: 'src',
                      expanded: false // this 
                  }
  </code></pre>
  
  <p>my json is good and working if not using <code>root</code> config like</p>
  
  <pre><code>({  "results": [
      { 
          id : '1' , 
          text : '1', 
          expanded: true, 
          results :[{ 
              id : '2' , 
              text : '2', 
              leaf:true
          }]
      },{ 
          id : '3' , 
          text : '3', 
          leaf:true
      }] 
  })
  </code></pre>
  
  <p>How to fix that thanks.</p>