hierarchical user roles

[TanyaStere42]

Context

Roles will be hierarchical, meaning you have one role, and each role comes with the permissions of the one below it.

User Story

• As a user manager or admin creating/editing a user’s account, I can only select one role:
  • Contributor: submit, maintain list of submissions
  • Researcher: matching, edit sightings, edit individuals
  • user manager: collaborations for others, edit users, reset passwords, see the /requests page
  • admin: all
• As a user, I have only the permissions associated with my given role

Technical notes

Migration: user gets the highest role they had previously
What to do with "staff"? can ignore or we can fold in to be admins.

Dependent stories:
Requires #932 and #933

[TanyaStere42]

creating and managing collaborations between other users needs to be covered by both user manager and admin