Jenkinsfile: update API version matrix; set default to v1.40
Jenkinsfile: update API version matrix; set default to v1.40

- Added new entry for Docker 19.03
- Removed obsolete engine versions that reached EOL (both
  as Community Edition and Enterprise Edition)
- Set the fallback/default API version to v1.40, which
  corresponds with Docker 19.03 (current release)

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

vdemeester/docker-py,docker/docker-py,docker/docker-py,vdemeester/docker-py