django_comment_client management command cleanup for Django 1.11

.../django_comment_client/management/commands/assign_role.py

...ent_client/management/commands/assign_roles_for_course.py

...t_client/management/commands/create_roles_for_existing.py

...comment_client/management/commands/get_discussion_link.py

..._comment_client/management/commands/reload_forum_users.py

...ment_client/management/commands/seed_permissions_roles.py

...go_comment_client/management/commands/show_permissions.py

...ango_comment_client/management/commands/sync_user_info.py