GET /api/admin/users as bob -> ["alice","bob"]
POST /api/admin/users {carol} as bob -> status=200 (id returned: true)
GET /api/admin/users as bob -> ["alice","bob","carol"]
carol logs in; realm_access={"roles":["offline_access","default-roles-demo","uma_authorization","user"]}
carol -> /api/reports status=200, /api/admin/users status=403
DELETE /api/admin/users/{id} as bob -> status=200
GET /api/admin/users as bob -> ["alice","bob"]
POST /api/admin/users as alice (no admin role) -> status=403