UserProvider so that any Opencast node can always resolve users supplied by LTI from a Sakai LMS
Updated provider code for 2.2.x is here:
https://bitbucket.org/cilt/opencast/src/33b9ba04652524b3d0ef7f9a6d7c3ac837da576c/modules/matterhorn-userdirectory-sakai/?at=r/2.2.x