Update nagios output to mention the nagios_level field
Update nagios output to mention the nagios_level field

joekiller/logstash-kafka,Aloomaio/logstash-kafka,joekiller/logstash-kafka,Aloomaio/logstash-kafka,tinglinux/logstash-kafka,tinglinux/logstash-kafka,opentable/logstash-kafka,opentable/logstash-kafka