added validation of SQS batch_events config parameter
added validation of SQS batch_events config parameter

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