title: Get user information in django templates
body: <p>What's the best way to get user information from a django template?</p>
  
  <p>For example, if I just want to:</p>
  
  <ol>
  <li>If the user is logged in, display "Welcome [username]"</li>
  <li>Otherwise, display the login button.</li>
  </ol>
  
  <p>I'm using django-registration/authentication</p>