Create a seed.js with required default data for every environment.

[davemcorwin]

User Story

As an operator I want new environments to have required seed data.

Background (Optional)

We observed an error in the admin interface when creating an organization because the default user and manager roles did not exist.

Acceptance Criteria

• [ ] We can seed data in an environment with yarn run seed
• [ ] Change made live via deploy federalist.

Level of effort - low

Implementation outline (if higher than "low" effort):

• [ ] add file scripts/seed.js (ideally idempotent)
• [ ] add script "seed": "node ./scripts/seed.js"
• [ ] Create required Roles in the seed file
• [ ] Remove Role creation from create-dev-data
• [ ] Update Readme where necessary