added explicit connection init to DataLoader::__new__
added explicit connection init to DataLoader::__new__

rfaulkner/wikipedia_user_metrics,wikimedia/analytics-user-metrics,wikimedia/user_metrics,rfaulkner/wikipedia_user_metrics,wikimedia/analytics-user-metrics,wikimedia/user_metrics,wikimedia/analytics-user-metrics,wikimedia/user_metrics,rfaulkner/wikipedia_user_metrics