RFE: config_stop should accept -c | --config argument and infer submission

[noblem]

Presently config_stop requires a submission ID, but that makes the command harder to use b/c one first has to look that up (either through FISS, the API, or UI). A more streamlined alternative would be to provide a flag which accepts the name of a config to stop, and from it look up the latest active submission IDs for that config, and stop the latest one (by default) or all of them (if --all flag is also given, or something)