Kafka Connect support

Would be great to have Schema Registry support for Kafka Connect.

I actually implemented it in our repo so we can run KC + SR integration tests: https://github.com/Segence/kafka-connect-kafka/tree/dev/src/integrationTest/scala/io/github/embeddedkafka/schemaregistry/connect

Please feel free to lift our code into this repo - would be great to have it in this library.