Lookup Kafka brokers from Zookeeper

Create a new ```Herman::Providers::JavaProducer``` object with the zookeeper info instead of broker ids.

This removes the functionality of instantiating the JavaProducer object with broker ids.
this is the best I could come up with from the zookeeper docs.  Practically, I tested it with "20" and it waited about that long, with 0 it just returned after the minimum amount of time.