Better integration testing

[bassosimone]

The MK binary we use for testing emits text but we probably want instead to get the raw stream of JSON messages. This would allow us to write a Python (or maybe golang) post processor that checks whether the output makes sense. This would allow to catch cases where, e.g., we fail to resolve the ASN or the CC because of human errors. I am not sure whether we could go down the road of injecting failures with the JSON API but maybe this could be a next step.