title: jQuery UI $(...).sortable is not a function with WebPack
body: <p>I believe I've set everything up correctly, but I'm getting an odd issue with Webpack.</p>
  
  <p>Consider this simple <code>app.ts</code> file:</p>
  
  <pre><code>'use strict';
  
  import $ = require('jquery');
  import 'jquery-ui';
  
  $(function() {
      $( "#sortable" ).sortable();
  });
  </code></pre>
  
  <p>Everything compiles fine, but when the site is run it complains that the <code>Uncaught TypeError: $(...).sortable is not a function</code>. (<code>sortable</code> is a jQuery UI function). </p>
  
  <p>Everything works fine when I instead link to a CDN hosted version of jQuery and jQuery UI, but it doesn't work when I use JS modules and Webpack. Why is this?</p>
  
  <p>Why is the jQueryUI function <code>sortable()</code> not recognized?</p>