Significant update of contests:
- Include '@id's of ballot measure contests (candidates already happening).
- Include '@id's of candidate and ballot measure contest selections.
- Updates and bug fixes for write-ins in candidate contests.
- Multi-candidate slates:
  - Combine names of candidates into list.
    Names are stored in lists even when there is only one candidate.
  - Combine parties of candidate IFF they are the same.
    Parties are always stored in lists, and empty if there is no party.

Only updates the JSON file not the custom data file.

See: https://github.com/trustthevote-project/nist-1500-100-103-examples/test_cases/september_test_case.json

- Candidate parties are now a list.
- 'write_in' -> 'is_write_in'

These are NOT intended to follow any standard, merely to aid in debugging.
There's an ongoing conversation about the format of human readable IDs.