title: Custom proxies on Stores and Models seems inconsistent (and does not work on Models)
body: <p>Am using Extjs 4, and have created a custom Rest Proxy to handle communication with my Zend backend api. 
  (See post <a href="http://techfrere.blogspot.com/2011/08/linking-extjs4-to-zend-using-rest.html" rel="noreferrer">http://techfrere.blogspot.com/2011/08/linking-extjs4-to-zend-using-rest.html</a>)</p>
  
  <p>When using a Store to handle communication, I was using Ext.require to load the proxy, and then referenced the proxy on the type field and all was good and it loaded my data: as per:</p>
  
  <pre><code>Ext.require('App.utils.ZendRest');
  ...
  proxy   : {
      type  : 'zest',              // My custom proxy alias
      url   : '/admin/user'
      ...
  }
  </code></pre>
  
  <p>I then decided to try to use the proxy directly on a model... and no luck. The above logic does not work.<br>
  Problems<br>
  1. When referencing zest, it does not find the previously loaded ZendRest class (aliased to proxy.zest)<br>
  2. It tries to load the missing class from App.proxy.zest (which did not exist.)<br>
  So I tried moving my class to this location and renaming to what it seemed to want. No luck.<br>
  It loads the class, but still does not initialize the app... I get no errors anywhere so v difficult to figure out where the problem is after this...  </p>
  
  <p>For now it seems I will have to revert to using my Zend Rest proxy always via the Store.</p>
  
  <p>Question is... has anyone else seen the behavior? Is it a bug, or am I missing something?</p>
  
  <p>Thanks...</p>