NetworkNatAddress network_id should be integer, not string.

[etrueskytap]

While mocking up data I discovered a compatibility issue. When a network interface is connected to a NAT network, it has a NAT address which we represent like this:

"nat_addresses": {
  "network_nat_addresses": [
  {
    "ip_address": "10.0.4.1",
    "network_id": 10846630,
    "network_name": "Default Network",
    "network_url": "https://cloud.skytap.com/configurations/18714628/networks/10846630",
    "configuration_id": 18714628,
    "configuration_name": "My Environment",
    "configuration_url": "https://cloud.skytap.com/configurations/18714628",
    "viewable": true
  }
],

The network_id in this data structure is an integer. This is an inconsistency in the REST API -- the network_id of the interface itself is a string. The NetworkNatAddress struct needs to accept an integer when parsing JSON.