PUBDEV-1843: grid testing.  There are cases where grid search returns no model.  In grid_search.py, the line grid_json['model_ids'][0] when executed will give an bad index error.  However, this does not tell the user that grid search has returned no model.  Add try catch to inform user when grid search has return no model.
PUBDEV-1843: grid testing.  There are cases where grid search returns no model.  In grid_search.py, the line grid_json['model_ids'][0] when executed will give an bad index error.  However, this does not tell the user that grid search has returned no model.  Add try catch to inform user when grid search has return no model.

h2oai/h2o-dev,h2oai/h2o-3,mathemage/h2o-3,mathemage/h2o-3,spennihana/h2o-3,h2oai/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,spennihana/h2o-3,spennihana/h2o-3,mathemage/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,spennihana/h2o-3,h2oai/h2o-dev,spennihana/h2o-3,jangorecki/h2o-3,jangorecki/h2o-3,michalkurka/h2o-3,jangorecki/h2o-3,h2oai/h2o-3,h2oai/h2o-3,jangorecki/h2o-3,mathemage/h2o-3,h2oai/h2o-3,spennihana/h2o-3,h2oai/h2o-dev,h2oai/h2o-dev,michalkurka/h2o-3,h2oai/h2o-dev,mathemage/h2o-3,h2oai/h2o-3,jangorecki/h2o-3,mathemage/h2o-3,jangorecki/h2o-3,jangorecki/h2o-3,h2oai/h2o-dev,spennihana/h2o-3,h2oai/h2o-3,mathemage/h2o-3,michalkurka/h2o-3,h2oai/h2o-dev