Add Support for Apache Kafka

[kamir]

Besides the following processing platforms:

[Java 8 Streams]
Apache Spark
GraphChi
Postgres
SQLite
Apache Flink

it is suggested to also support Apache Kafka.

This issue is considered to be an umbrella for other issues, related to that topic. I expect it to be open for some time, until we can say: Apache Wayang supports Apache Kafka as a processing platform (even if today it is not yet 100% clear in which scope that will be)