Add config.yml.example and sets admin permissions
This commit adds the following:
1. Adds update_user method in auth.py to set admin permissions for
new accounts and pre-existing accounts of admin users. It also
clears the permissions when a user is removed from the admin list.
2. A config.yml.example is added to get the admin list in auth.py and ADMINS
in settings/base.py
3. Adds documentation to create file config.yml using config.yml.example.
4. Adds login to Django Admin Site using OIDC and refactoring login code from
view.py.