title: ExtJs BufferedStore fetching descending by id
body: <p>I have REST service with some data:  </p>
  
  <pre><code>[{id:20},{id:16},{id:14},{id:11},{id:9},{id:8}]
  </code></pre>
  
  <hr>
  
  <p>request (get data with id less then 15) </p>
  
  <pre><code>?fromId=15&amp;count=3
  </code></pre>
  
  <p>response</p>
  
  <pre><code>[{id:14}, {id:11},{id:9}]
  </code></pre>
  
  <hr>
  
  <p>request (no fromId means get last data)</p>
  
  <pre><code>?count=3
  </code></pre>
  
  <p>response</p>
  
  <pre><code>[{id:20},{id:16},{id:14}]
  </code></pre>
  
  <hr>
  
  <p>Is there any way to use BufferedStore with this API (I use it with gridpanel)?
  The main question is how to make store requests with descending fromId.</p>
  
  <p><strong>UPD</strong>:
  I have to get infinite scrollable grid panel with this data. But have no idea how to configure proxy and store for it.
  Is it possible or I should override some methods to fill request manualy?</p>
  
  <p><strong>UPD Store:</strong></p>
  
  <pre><code>Ext.define('Admin.store.OrderStore', {
  extend: 'Ext.data.BufferedStore',
  model: 'Admin.model.Order',
  alias: 'store.order',
  autoLoad: true,
  autoDestroy: true,
  remoteSort: true,
  remoteFilter: true,
  proxy: {
      type: 'rest',
      url: 'api/order',
      limitParam: 'size',
      startParam: 'fromId',
      extraParams: {
          filter: {}
      },
      reader: {
          type: 'json',
          rootProperty: 'data',
          totalProperty: 'total'
      }
  }
  </code></pre>
  
  <p>});</p>