Keepalive check missing issued & executed timestamps

[portertech]

The keepalive check is missing issued & executed timestamps. Keepalive checks are a special case, as they are created and maintained by the Backend.

Using the latest master Docker image:

[portertech]

Related but not applied to Backend keepalive checks a58c538

[mercul3s]

Ah, that's probably also affecting the keepalive check history as well. This is what a keepalive check looks like as json output:

"check": {
    "check_hooks": null,
    "duration": 0,
    "environment": "default",
    "handlers": [
      "keepalive"
    ],
    "high_flap_threshold": 0,
    "history": [
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {},
      {}
    ],
    "interval": 120,
    "issued": 0,
    "last_ok": 1525379486,
    "low_flap_threshold": 0,
    "metric_handlers": null,
    "name": "keepalive",
    "occurrences": 1,
    "occurrences_watermark": 1,
    "organization": "default",
    "proxy_entity_id": "",
    "publish": false,
    "round_robin": false,
    "runtime_assets": null,
    "state": "passing",
    "status": 0,
    "stdin": false,
    "subdue": null,
    "subscriptions": [],
    "timeout": 0,
    "total_state_change": 0,
    "total_state-change": 0
  }