Master branch: logstash output to unresolvable host -> events seen as sent and checkpointed

[reflection]

config.yml

filebeat:
  prospectors:
    -
      input_type: log
      paths:
        - /var/log/dnf.log

output:
  logstash:
    hosts: ["unresolvable:8001"]

logging:
  level: info

sudo ./filebeat -c config.yml -e

2016/01/27 21:41:10.005930 transport.go:50: WARN DNS lookup failure "unresolvable": lookup unresolvable: No address associated with hostname
2016/01/27 21:41:10.005956 single.go:124: INFO Connecting error publishing events (retrying): lookup unresolvable: No address associated with hostname
2016/01/27 21:41:10.005959 single.go:146: INFO send fail
2016/01/27 21:41:10.005963 single.go:153: INFO backoff retry: 8s
2016/01/27 21:41:17.959374 prospector.go:94: INFO Run prospector
2016/01/27 21:41:18.006066 publish.go:104: INFO Events sent: 79
2016/01/27 21:41:18.006159 registrar.go:150: INFO Registry file updated. 1 states written.

Behavior is correct in 1.0.1.