title: ExtJS - grid empty but store loaded
body: <p>My grid is not filled, though the store is filled with json data. What is wrong?
  I want all data from <code>"csv":[...]</code> to be written to the grid columns.
  If I <code>console.log()</code> the store, my json data is located at <code>store.proxy.reader.[jsonData|rawData].data.csv</code> => Array[4]</p>
  
  <p>Json Data:</p>
  
  <pre><code>{"status":{"status":0,"msg":"Ok","protocolversion":"1.1.json"},"data":{"headline":{"headline":"headline"},"csv":[{"key":"0","value":"...lugin\/monitor\/files\/logfilefilter_worker_error.log"},{"key":"1","value":"...les\/logfilefilter-worker01-progress.log.1331769600"},{"key":"2","value":"...\/application\/x\/plugin\/monitor\/files\/Test.log"},{"key":"3","value":"...ind\/plugin\/monitor\/files\/logfile_for_navi_test.log"}]}}
  </code></pre>
  
  <p>Model:</p>
  
  <pre><code>Ext.define( 'Monitor.model.ComboLogfiles', {
    extend: 'Ext.data.Model',
    fields: [ {name: 'key'}, {name: 'value'} ] 
   } );
  </code></pre>
  
  <p>Store:</p>
  
  <pre><code>Ext.define( 'Monitor.store.ComboLogfiles', {
    extend  : 'Ext.data.Store',
    model   : 'Monitor.model.ComboLogfiles',
    proxy   : {
       type       : 'ajax',
       url        : '/devel/phi/dev/04-presentation/http-api/index.php',
       extraParams: {
          user      : 'test',
          pass      : 'test',
          vers      : '1.1.json',
          module    : 'monitor',
          func      : 'getLogfiles'
       },
       reader     : {
          type: 'json',
          root: 'csv'
          // root: 'data'
       }
  
    },
    autoLoad: true
  } );
  </code></pre>
  
  <p>Controller</p>
  
  <pre><code>var store = Ext.create('Monitor.store.ComboLogfiles');
  
  oLogfileSelector = Ext.create("Ext.window.Window", {
          title: 'Logfiles',
          width: '200',
          height: '400',
          autoScroll: true,
          flex: 1,
          minimizable: false,
          maximizable: false,
          style: 'background-color: #fff;',
          items: [{
                xtype: 'panel',
                items: [
                   Ext.create('Ext.grid.Panel', {
                      id: 'mygrid',
                      store: store,
                      width: 200,
                      height: 200,
                      title: 'Logfiles',
                      columns: [
                         {
                               text: 'Key',
                               width: 50,
                               sortable: false,
                               dataIndex: 'key'
                         }
                         ,{
                               text: 'File',
                               width: 100,
                               sortable: false,
                               dataIndex: 'value'
                         }
                      ]
                   })
                ]
  
          }]
  
       }).show();
  </code></pre>