Output format optimization

[HanadaLee]

1. rename as_domain to autonomous_system_domain

"asn": {
    "autonomous_system_number": <uint32>,
    "autonomous_system_organization": "...",
    "autonomous_system_domain": "..."
  },

2. postal codes are a type of location, and I personally don't think they need to be placed in the top-level label.

  "location": {
    "accuracy_radius": <uint16>,
    "latitude": <double>,
    "longitude": <double>,
    "metro_code": <uint16>,
    "time_zone": "...",
    "postal_code": "..."
  },