Add async helper to test_sock_path_len
Add async helper to test_sock_path_len

This test function is causing another test:

unit.utils.test_event.TestAsyncEventPublisher.test_event_subscription

To fail with 'Async operation timed out after 5 seconds', Adding the
tornado Async test helper so that both tests pass.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt