This commit is a rough port to Django 2.1, Python 3 and a Docker based local
development setup. Tests fail/error but migrations and the web frontend are
already runnable. Task queue functionality is untested and translations seem to
have trouble.
- implement delete method and let it call these tasks:
- disable_web_vhost
- delete_web_vhost_config
- delete_file_website_hierarchy
- delete_web_php_fpm_pool_config if this was the last website of the
user
- implement save method and let it call these tasks:
- create_web_php_fpm_pool_config if the user has no website yet
- create_file_website_hierarchy
- create_web_vhost_config
- enable_web_vhost
