title: Exclude react from webpack bundle
body: <p>I'm trying to exclude react from my bundle which is generated by webpack. Reason being, we have a global version of react available on the page so I'll be using that. </p>
  
  <p>I have tried using the below, as suggested here <a href="https://stackoverflow.com/questions/22530254/webpack-and-external-libraries">Webpack and external libraries</a> but this doesn't seem to work. I can see webpack has exported React but it still 
  appears in the bundle. </p>
  
  <pre><code>externals: {
    'react': 'React'
  }
  </code></pre>
  
  <p>I was thinking it may be another dependency e.g. react-router importing react? Has anyone managed to do this?</p>