Update how users login to airflow instance

[edsu]

Currently users are logging into Airflow with the same dummy account credentials. In an ideal world specific users would be granted access using Stanford's Single Sign On, as they access other DLSS sites.

[peetucket]

Not impossible to use SSO with workgroups instead of username/password, but will be work (John investigated during libsys airflow project, and it was a bit complicated)