Add @type:ci_latency_monitor_bot parser

The monitor-bots are currently [shipping in data using lumberjack](http://logsearch.cityindextest5.co.uk/#dashboard/temp/Qf4OvWs9RMCm27lQtNOniQ), which has the following shape:

```json
{
  "_index": "logstash-2013.11.25",
  "_type": "ci_latency_monitor_bot",
  "_id": "IMdBcFMmQkG9ve42M3Jh_A",
  "_score": null,
  "_source": {
    "@timestamp": "2013-11-25T22:55:04.680Z",
    "@version": "1",
    "@source_host": "AndreiCfTest",
    "@type": "ci_latency_monitor_bot",
    "@environment": "PPE",
    "@source_lonlat": "0.5,0.5",
    "@source.host": "17bi4ct7vv7",
    "@source.path": "/home/vcap/tmp/tmp.logsearch-ciapi_latency_monitor-bot/data/38log.txt",
    "@source.offset": "1399201",
    "@message": "2013-11-25 22:55:00.299 Latency General.StaticPage: 0.085852"
  },
  "sort": [
    1385420104680
  ]
}
```

This parser should extract the timestamp and measurement from the @message, and convert the @source_lonlat into an array