Create a new container authN filter which authenticates against K2:
We have the K2 service to track users by cookies.
1. Add something on the Sakai 2 side that pulls the tracking cookie
from the request and calls /var/cluster/user?c=<cookie> to get the
Sakai 3 user object for that cookie. That URL will ultimately be
password protected so that the Sakai2 side has its own username and
From the user object in json form Sakai 2 should be able to log in a
user in and do anything else necessary.
This could either be a Filter or a UserDirectoryProvider.