Wait command failure

[JulienBalestra]

Describe what happened:

When using pupernetes wait before pupernetes.service actually started, go-systemd returns a dead state.

+ sudo -kE pupernetes wait --unit-to-watch pupernetes.service --logging-since 2h --timeout 20m
E0613 15:47:43.809421     958 wait.go:93] Unexpected state of systemd job: systemd job pupernetes.service is dead
E0613 15:47:43.819300     958 main.go:27] Exiting on error: 2

So we may dig into the unit status returned by the library to check if the systemd service should start soon.