title: React Native Fetch Request Fails
body: <p>I am using the react native Fetch API to get JSON data from  <code>https://api.github.com/users/{username}</code> but the request fails with the following error message.</p>
  
  <blockquote>
    <p>"TypeError: Network request failed {stack: (...), message: 'Network
    request failed'}".</p>
  </blockquote>
  
  <p>I believe for https, sometimes you get <strong>NSURLAuthenticationChallenge</strong>. I am not sure how to implement this. Anyone have any idea about this?</p>