#301: data_validator.py, use 'try-except' to ensure valid file
#301: data_validator.py, print message, and 'sys.exit()'
#301: data_validator.py, minor language change
#301: data_validator.py, minor language change
Merge pull request #308 from jeff1evesque/python_data_validator

#301: Ensure 'json_file_obj' exists