Implement automatic exports for `simulate_experiment_responses` and async tasks?

[pzingg]

Should the client export automatically, to a CSV file with a well-known name, like "auto_simulated_.csv", if the auto_export_path option is set? Currently the 'auto_export_path' only works when tasks are polled.

Also, not sure if auto_export_path does anything if the run_tasks_async option is set. Need to test that combination.