title: Sencha Touch list store disable sorting
body: <p>I have my list which is getting data from php service, the data received is in the order I need. But sencha automatically sort my list alphabetically. 
  Below is my code:</p>
  
  <pre><code>Ext.define('MyList', {
      extend: 'Ext.dataview.List',
  
      config:     {
          grouped: true,
          plugins: [
              {
                  xclass:          'Ext.plugin.PullRefresh',
                  pullRefreshText: 'Pull down to refresh'
  
              },
              {
                  xclass:     'Ext.plugin.ListPaging',
                  autoPaging: true,
                  noMoreRecordsText: 'No More Records'
  
              }
          ]
      },
      initialize: function () {
          this.callParent(arguments);
          var store = Ext.create('Ext.data.Store', {
  
              pageParam: 'page',
              grouper: {
                  groupFn: function (record) {
                      return record.data.group_label;
                  }
              },
              model:   'ListItem',
              proxy:   {
                  type:   'ajax',
                  url:    '/m/services/activity_list_items.php',
                  reader: {
                      type:         'json',
                      rootProperty: 'root.results'
                  }
              }
          });
  
          var template = Ext.create('GenericListItem', {
              hascounts: true,
              hasicon:   true,
              varmap:    {
                  descr:  'subtext',
                  count:  'sub_item_cnt',
                  itemid: 'itemid',
                  uniqid: 'uniqid'
              }
          });
  
          var emptyText = 'Recent Activity Items';
          this.setStore(store);
          this.setItemTpl(template);
          this.setEmptyText(emptyText);
      }
  });
  </code></pre>
  
  <p><strong>How can I avoid the auto sorting of list?</strong></p>