Phase 2: Withings sync update

Relies on: https://github.com/ijustwanttocode/whyeatthings/pull/74

- Health Accounts controller manages the accounts a user has
- If exists, you can import and delete
- If not exists, you can authorize and a credential will be stored from the user.  This logic was removed from the dashboards controller and the import action.
Remove this in your next pass