Added support for milliseconds
Added support for milliseconds

Parsed the nanosecond part to obtain millisecond accuracy. Also
removed redundant casting to integer

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