allow apache access logs with an invalid referer: field
allow apache access logs with an invalid referer: field

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