Similar to status-is except that the HTTP status can be one of a list, instead of just one fixed value.
Usecase: a Sympa server with CAS authentication set. Without a sympa_session cookie, you get a 302 status,
with it, you have a 200 status.
Argos will first try the given config file (given either with `--config` or with
`ARGOS_YAML_FILE` env var), then `argos-config.yaml`, then `/etc/argos/config.yaml`.
