title: React PropTypes.oneOf to specify an enum doesn't work
body: <p>I have a problem to specify a property of type 'enum' in react. According to the documentation here <a href="https://facebook.github.io/react/docs/reusable-components.html" rel="noreferrer">React multiple components </a>the following snippet should work :</p>
  
  <pre><code>position : React.PropTypes.oneOf(['rightTop','rightBottom'])
  </code></pre>
  
  <p>But I get the following error </p>
  
  <pre><code>ERROR in ./app/components/mqttComponents/mqttPresence.jsx
  Module build failed: SyntaxError:/Users/giuseppe/Projects/sw-director/app/components/mqttComponents/mqttPresence.jsx: Unexpected token (68:36)
  66 |   propTypes : {
  67 |     //position: React.PropTypes.string.isRequired,
  &gt; 68 |     position : React.PropTypes.oneOf(['rightTop','rightBottom']),
                                             ^
   69 |     showMqttClientStatus : React.PropTypes.bool.isRequired,
   70 |     mqtt: React.PropTypes.object
   71 |   }
  </code></pre>
  
  <p>I don't realise which is the error? Maybe is something related to the new ES6 syntax ?</p>