title: Django: Add user to group via Django Admin
body: <p>How can I add users to a group in Django admin interface of "Change Group"?</p>
  
  <p>I have seen dirty hacks to get this working for older django version.</p>
  
  <p>How to solve this with Django 1.10?</p>
  
  <p>Emphasize: I want this on the page "Change Group", not on "Change User".</p>
  
  <p>I would like to have this in django-admin-style: No coding, just doing some configuration. Maybe like this:</p>
  
  <pre><code>class GroupAdmin(admin.ModelAdmin):
      show_reverse_many_to_many = ('user',)
  </code></pre>