Producer should not retry when required_acks is 0
Producer should not retry when required_acks is 0

required_acks 0 means the producer never waits acks from the brokers.
Previous code causes duplicated messages because buffer isn't updated
by producer opertaions with required_acks 0

crashlytics/ruby-kafka,crashlytics/ruby-kafka,zendesk/ruby-kafka,zendesk/ruby-kafka