Merged in kidmose/pywhois/feature/test-missing-keys (pull request #33)
test_parser.py: Fail on missing keys
{"domain_name": "YANDEX.RU", "expiration_date": "2018-09-30 21:00:00", "updated_date": null, "creation_date": "1997-09-23 09:45:07", "status": "REGISTERED, DELEGATED, VERIFIED"}