Add the flexibility of multiple roles

I have code that creates roles, and users can have multiple roles. It also checks if they have the administrator role, rather than using a flag on the user row.
If this is useful to add to the template, let me know and I can add it through a PR.

No files or tests are named. Start by locating the current user-role model and administrator check in the template, then review the proposed multiple-role behavior; done means the intended role representation and authorization behavior are agreed and covered by relevant tests.

Written by the indexing model from the issue text.