Add delay to command for rolling updates

[kierenevans]

Quotes flask rollout for https://github.com/eficode-academy/kubernetes-katas/blob/master/rolling-updates.md is very very fast, we should introduce a delay so it's more obvious what's going on, e.g. override the command run to be bash -c "sleep 5 && the-command" or similar.

Could even introduce an initContainer for this purpose, or a preStop hook?