admin panel: db, models, routes

[Nalipp]

create seed data with existing data model in data.sql connect basic endpoints to react admin panel

[stephaniesimms]

• [x] seed data for users, charges, salaries
• [x] script to seed db
• [x] tests
• [x] user model: find, update, delete (auth @emitamago @mvatanya)
• [x] user routes: get, post, patch, delete
• [x] salaries model: find all, update, delete
• [x] salaries routes: get, post, patch, delete
• [ ] charges model: find all, update, delete
• [ ] charges routes: get, post, patch, delete

[stephaniesimms]

all tasks completed as part of related issue #29 charges model, routes, tests are part of new issue #39