[WIP]  Add PUT and POST api routes

- [x] Add PUT `/checks` route (create a new check)
- [x] Add POST `/checks/:id` route (update a new check)
- [ ] Refactor dashboard app to use `populateFromDirtyCheck` instead of `populateCheckFromRequest`
- [x] Add unit tests for `populateFromDirtyCheck` method
- [ ] Add functional tests for api routes (wip)