The initial MVP of ltd-keeper had all-or-nothing authentication; any user was effectively an admin user. It would be useful have fine grained roles that each API user could have (for example, one API user might be able to add a build, but not create an edition or product or add another user). The phases of this ticket at:

1. Design a set of roles that cover current functionality
2. Add these roles to the User DB model and user creation API
3. Authorize users against these roles in specific API calls