Users should be uniquely identified using UIN

[wwelling]

Right now, Vireo 4 utilizes 'email' to uniquely identify users. This will cause issues due to the fact that A&M recycles emails. It would be better to have a user property for unique identification. UIN is a good value for this purpose.

This task will require making it configurable to use netid as a unique identifier for user. Updating when a user is authenticated from SSO to lookup user by the unique identifier (email or netid). The UIN will be stored in the netid from the SP and be available the same as netid is currently found in the shibboleth payload/credentials.