Improve logging in CVModelBuilder.
Improve logging in CVModelBuilder.

h2oai/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,h2oai/h2o-3