Identify a way to mark the "role" of a User within a Data Trust

[reginafcompton]

A Facet User should be able to see the "role" of other users, e.g., member, trustees, nothing....

For the short term, I can envision two solutions:

1. we add a UserType/UserRoles table (which describes the different roles in a datatrust: member, trustee...): each user would have a foreign key that points to an entry in this table. Does this violate the spirit of the Authserver?
2. we add a string field in the User model

For the long term, we may want to use the Data Trust Management API (formerly "Facet backend") to track this.