Add NIC configuration information to Machine

[ymmt2005]

This PR adds NIC configuration information to Machine.Info.

The information can be referenced from Ignition templates to configure network.

gateway-offset in dhcp.json is moved to ipam.json.
This impacts existing users (if any).

The data format stored in etcd is slightly changed.
To convert old data automatically, the PR also introduces "schema version".

The first schema version is "2" considering old data are made
with schema version "1".

[ymmt2005]

dctest 上で動作確認。

Before:

$ sabactl machines get --serial "fb8f2417d0b4db30050719c31ce02a2e8141bbd8" | jq '.[0].info'
{
  "bmc": {
    "ipv4": {
      "address": "10.72.17.3",
      "netmask": "255.255.240.0",
      "gateway": "10.72.16.1"
    }
  }
}

$ sabactl ipam get
{
  "max-nodes-in-rack": 28,
  "node-ipv4-pool": "10.69.0.0/20",
  "node-ipv4-range-size": 6,
  "node-ipv4-range-mask": 26,
  "node-ip-per-node": 3,
  "node-index-offset": 3,
  "bmc-ipv4-pool": "10.72.16.0/20",
  "bmc-ipv4-offset": "0.0.1.0",
  "bmc-ipv4-range-size": 5,
  "bmc-ipv4-range-mask": 20,
  "bmc-ipv4-gateway-offset": 1
}

バージョンアップ：

$ sudo ./sabakan --config-file=/etc/sabakan/config.yml
2019-02-13T02:23:58.760406Z boot-0 sabakan info: "upgrading schema version" from="1" to="2"
2019-02-13T02:23:58.867119Z boot-0 sabakan info: "updated schema version" to="2"
2019-02-13T02:23:58.894676Z boot-0 sabakan info: "resume stateful watching" rev=510

After:

$ ./sabactl machines get --serial "fb8f2417d0b4db30050719c31ce02a2e8141bbd8" | jq '.[0].info'
{
  "network": {
    "ipv4": [
      {
        "address": "10.69.0.3",
        "netmask": "255.255.255.192",
        "maskbits": 26,
        "gateway": "10.69.0.1"
      },
      {
        "address": "10.69.0.67",
        "netmask": "255.255.255.192",
        "maskbits": 26,
        "gateway": "10.69.0.65"
      },
      {
        "address": "10.69.0.131",
        "netmask": "255.255.255.192",
        "maskbits": 26,
        "gateway": "10.69.0.129"
      }
    ]
  },
  "bmc": {
    "ipv4": {
      "address": "10.72.17.3",
      "netmask": "255.255.240.0",
      "maskbits": 20,
      "gateway": "10.72.16.1"
    }
  }
}

$ ./sabactl ipam get
{
  "max-nodes-in-rack": 28,
  "node-ipv4-pool": "10.69.0.0/20",
  "node-ipv4-range-size": 6,
  "node-ipv4-range-mask": 26,
  "node-ip-per-node": 3,
  "node-index-offset": 3,
  "node-gateway-offset": 1,
  "bmc-ipv4-pool": "10.72.16.0/20",
  "bmc-ipv4-offset": "0.0.1.0",
  "bmc-ipv4-range-size": 5,
  "bmc-ipv4-range-mask": 20,
  "bmc-ipv4-gateway-offset": 1
}