title: ExtJS 5 Upgrade - Viewport unrecognized class name / alias
body: <p>My application is working fine in ext js 4.2.1 but when I upgrade I am unable to get the viewport to load correctly. The view port is in a different file and loads initially but then I get the </p>
  
  <blockquote>
    <p>Error: [Ext.create] Unrecognized class name / alias: App.view.MainViewport</p>
  </blockquote>
  
  <p>I have tried requiring the the viewport file but that is not working. Any help would be much appreciated.</p>
  
  <p>app.js</p>
  
  <pre><code>Ext.Loader.setConfig({enabled: true)};
  Ext.Loader.setPath('Ext.ux', 'extjs5.1.1/ux');
  Ext.require(['Ext.tip.QuickTipManager','Ext.container.Viewport', 'Ext.plugin.Viewport','Ext.layout.*','Ext.form.Panel','Ext.form.Panel', 'Ext.form.Label','Ext.grid.*','Ext.data.*','Ext.tree.*','Ext.selection.*', 'Ext.tab.Panel','Ext.ux.TabCloseMenu'] );
  Ext.onReady( function() {
     Ext.application({
       name : 'App',
       appFolder: 'extapp',
       launch: function() {
         Ext.create('App.view.MainViewport');
       }
     });
  });
  </code></pre>
  
  <p>MainViewport.js</p>
  
  <pre><code>Ext.define('App.view.MainViewport', {
     extend : 'Ext.container.Viewport',
     alias : 'widget.MainViewport',
     layout: {
       type: 'border'
     },
     initComponent: function() {
         console.info("initializing view");   
     }
  });
  </code></pre>