Add the option to set client.id to storm-kafka

[carl34]

Add the ability to set the Kafka client.id property to storm-kafka and storm-kafka-client (https://issues.apache.org/jira/browse/STORM-2524).

storm-kafka example:

	SpoutConfig spoutConfig = new SpoutConfig(
		brokers,
		topicConfs.topic,
+		"client_id-" + confs.consumerGroupId + "-" + topicConfs.topic,
		"/consumers",
		confs.consumerGroupId + "-" + topicConfs.topic
	);

storm-kafka-client example:

	KafkaSpoutConfig<String,String> kafkaSpoutConfig = KafkaSpoutConfig.builder(KAFKA_LOCAL_BROKER, TOPIC)
		.setGroupId(confs.consumerGroupId + "-" + topicConfs.topic)
+		.setClientId("client_id-" + confs.consumerGroupId + "-" + topicConfs.topic)
		.build();

[carl34]

See #2126, attempting to resolve CHANGELOG.md merge conflicts.