FH-3785 Add sync stats endpoint

[aidenkeating]

• Add /sys/info/stats endpoint that invokes sync.getStats()
• Add default server port, 3000

[aidenkeating]

@david-martin Would you mind taking a look? This is adding the stats endpoint to be used in the MCP.

At the moment the response before an initial sync (before the redis client is initialised) can be quite messy, so this PR will include a bump to use feedhenry/fh-sync#33 when it's merged.

The current response from fh-sync-js has a lot going on.

An example of what the response looks like currently:

{
  "CPU usage": {
    "message": "no stats available"
  },
  "RSS Memory Usage": {
    "master": {
      "current": "62.04MB",
      "max": "79.25MB",
      "min": "47.55MB",
      "average": "53.49MB",
      "numberOfRecords": 832,
      "from": "2017-08-16T09:01:10.157Z",
      "end": "2017-08-16T10:24:38.534Z"
    }
  },
  "Job Process Time": {
    "sync_worker": {
      "current": "18.00ms",
      "max": "36.00ms",
      "min": "6.00ms",
      "average": "9.26ms",
      "numberOfRecords": 384,
      "from": "2017-08-16T09:01:05.504Z",
      "end": "2017-08-16T11:02:28.078Z"
    },
    "pending_worker": {
      "current": "49.00ms",
      "max": "49.00ms",
      "min": "3.00ms",
      "average": "22.67ms",
      "numberOfRecords": 3,
      "from": "2017-08-16T09:01:05.466Z",
      "end": "2017-08-16T11:02:28.043Z"
    },
    "ack_worker": {
      "current": "2.00ms",
      "max": "2.00ms",
      "min": "1.00ms",
      "average": "1.50ms",
      "numberOfRecords": 4,
      "from": "2017-08-16T09:01:38.262Z",
      "end": "2017-08-16T09:03:52.108Z"
    }
  },
  "Job Queue Size": {
    "ack_worker": {
      "current": 0,
      "max": 0,
      "min": 0,
      "average": 0,
      "numberOfRecords": 333,
      "from": "2017-08-16T09:56:17.502Z",
      "end": "2017-08-16T10:24:38.566Z"
    },
    "pending_worker": {
      "current": 0,
      "max": 0,
      "min": 0,
      "average": 0,
      "numberOfRecords": 333,
      "from": "2017-08-16T09:56:17.501Z",
      "end": "2017-08-16T10:24:38.565Z"
    },
    "sync_worker": {
      "current": 1,
      "max": 1,
      "min": 0,
      "average": 0.059880239520958,
      "numberOfRecords": 334,
      "from": "2017-08-16T09:56:12.502Z",
      "end": "2017-08-16T10:24:38.564Z"
    }
  },
  "API Process Time": {
    "message": "no stats available"
  },
  "Mongodb Operation Time": {
    "message": "no stats available"
  }
}