asn — ASN lookup with RPKI validation

Usage:
  curl asn.fenleytech.com/<ASN>              plain-text report
  curl asn.fenleytech.com/<ASN>?format=json  JSON

<ASN> may be given as 13335 or AS13335.

Data: announced prefixes and peers from RIPEstat, aggregated with
aggregate-prefixes, RPKI validity from a local Routinator instance.