title: How to list all GitHub users?
body: <p>I'm working on a site, need to crawl all user information (at least the user on our site) from GitHub. I searched GitHub API, and found no answer.</p>
  
  <p>So is there any way I can do this job? 
  I only have the users emails. (I can check user by compare the email hash with gravatar URL)</p>
  
  <ol>
  <li>I had send email to GitHub support, and got no answer currently.</li>
  <li>I only need know the usernames, I can use GitHub API to get other informations.</li>
  </ol>