HDFS System Producer should not have Kafka dependency

Currently HDFSSystemFactory has seemly unnecessary dependency on Kafka:

def getProducer(systemName: String, config: Config, registry: MetricsRegistry) =

{ val clientId = KafkaUtil.getClientId("samza-producer", config) val metrics = new HdfsSystemProducerMetrics(systemName, registry) new HdfsSystemProducer(systemName, clientId, config, metrics) }

Should try to get rid of the dependency