cmd/scollector: Fixed bug in ElasticSearch collector for Elastic 5.x: (#2155)
cmd/scollector: Fixed bug in ElasticSearch collector for Elastic 5.x: (#2155)

Elastic 5.x route of `/_nodes/_local/stats` emits a single IP address,
such as

```
"ip": "10.7.1.74:9300"
````

However prior to v5 this is an array:

```
"ip": [
	"10.7.1.74:9300"
],
```

We do not use the IP address attribute from this route anywhere in the
collector, so removing it from the JSON decoding stops the error, and has no
impact on the collectors functionality (apart from making it work again).
mhenderson-so/bosun,bosun-monitor/bosun,bosun-monitor/bosun,bookingcom/bosun,bosun-monitor/bosun,mhenderson-so/bosun,mhenderson-so/bosun,mhenderson-so/bosun,bosun-monitor/bosun,bosun-monitor/bosun,bookingcom/bosun,bookingcom/bosun,bosun-monitor/bosun,mhenderson-so/bosun,bookingcom/bosun,bookingcom/bosun,mhenderson-so/bosun,bookingcom/bosun