title: How should material-ui be externalized when bundling with webpack
body: <p>I packed material-ui from <code>material-ui/index.js</code> into material-ui.js for serving it externally.
  The import statements are like</p>
  
  <pre><code>import FlatButton from 'material-ui/FlatButton';
  </code></pre>
  
  <p>How should webpack be configured to exclude material-ui as external dependency?\ I believe changing imports as this would help in externalizing but have no idea how to deal with material-ui thereafter.</p>
  
  <pre><code>import material-ui from 'material-ui'
  </code></pre>