No support for Check Runs

[aberenshtein]

On Oct 4th: https://blog.travis-ci.com/2018-09-27-deprecating-github-commit-status-api-for-github-apps-managed-repositories
and this is the new endpoint:
https://developer.github.com/v3/checks/runs/#list-check-runs-for-a-specific-ref

When can we add support for this endpoint

[piotrmurach]

Thanks for using this gem!

Please submit PR implementing new API and I will release quickly.