title: Add permissions to the default group in django using post_save signals
body: <p>I created two groups using post_save signals in django. My default groups name are: 'members' and 'managers'. Now I try to add default permissions to the default gropu 'members'. So far I did:</p>
  
  <pre><code>@receiver(post_save, sender=settings.AUTH_USER_MODEL)
  def add_to_default_permission(sender, **kwargs):
      members = kwargs["instance"]
      if kwargs["created"]:
          permission1 = Permission.objects.get(name='Can add person')
          permission2 = Permission.objects.get(name='Can change person')
          permission3 = Permission.objects.get(name='Can add child')
          permission4 = Permission.objects.get(name='Can change child')
          permission5 = Permission.objects.get(name='Can delete child')
          members.permissions.add(permission1, permission2,permission3,permission4,permission5)
  </code></pre>
  
  <p>But when I tried to create superuser, it gives errors:</p>
  
  <pre><code>in add_to_default_permission
          members.permissions.add(permission1, permission2,permission3,permission4,permission5)
      AttributeError: 'User' object has no attribute 'permissions'
  </code></pre>
  
  <p>How could I fix this error. Any advice will be much appreciated. </p>