Add support for spec:integration to ignore MRI and Java cases off their respective platforms
Update the Hermann::Discovery::Zookeeper API to return an Array of brokers more suitable for Hermann::Producer
Refactor the Hermann::Producer Java-based integration test to respect integration.yml

I've also refactored/cleaned it up a bit to make sure it runs properly on my machine
Add a failing integration test for pumping protobufs through Hermann
Catch all Java related exceptions and raise them up out of Hermann::Producer#push_single
Properly marshal bytes in and out of the Kafka client library

The primary issue with marshalling bytes back and forth previously was the use
of the StringEncoder class. By default the Kafka client library uses the
DefaultEncoder which is a no-op and simply allwos byte arrays through