add worker config for liveness/readinessProbe
This MR adds a separate livenessProbe and readinessProbe for each worker, and it also adds support for exec probe. The reason is that there's a good chance your worker has different livenessProbe check than your website, currently, you can't set httpGet probe for your website and a different one for your worker.
Fixes #55 (moved)
Edited by Shinya Maeda