title: Django Rest JWT login using username or email?
body: <p>I am using <strong>django-rest-jwt</strong> for authentication in my app.</p>
  
  <p>By default it user username field to autenticate a user but I want let the users login using <strong>email or username</strong>.</p>
  
  <p>Is there any mean supported by django-rest-jwt to accomplish this.
  I know the last option would be write my own login method.</p>