Add support for Kafka 0.9.0 group management

[horkhe]

New set of API was introduced in Kafka 0.9.0 that allows using Kafka for consumer group management and leaving clients free of direct communication with ZooKeeper. It should be possible to make Kafka-Pixy use this API.

[Paxa]

Would be nice to have, so connection to zookeeper will be optional

[horkhe]

@Paxa thank you for your feedback, although I won't lie to you that is not going to happen soon. I am too busy with other projects and ZooKeeper works just fine. Besides it is not like you can get rid of ZooKeeper even if Kafka-Pixy made to use the consumer group Kafka API, for Kafka itself still needs ZooKeeper.

Just curious, are you using Kafka-Pixy in some project?

[Paxa]

just wanted to try because kafka connection is complex. All consumers that I have now talk just to kafka (ruby lib, kt, rust lib)
Afaik for kafka-pixy it should be enough just talk to brokers, but may be I don't know something

[horkhe]

When support for this API is implemented, then Kafka-Pixy will only connect to Kafka brokers, but for now it needs to connect to ZooKeeper too.

When you have tried it, it would be great if you can share your experience.