Merge pull request #670 from jeff1evesque/python_data_validator

#654: Add jsonschema for 'data_validation' method
#671: config.py, correct method names
Merge pull request #672 from jeff1evesque/python_config

#671: config.py, correct method names
#628: data_validator.py, change 'prelearning_data_validation' -> 'dataset_validation'