STORM-303: Forward port of storm-kafka work.

This is a port of my work from
https://github.com/brndnmtthws/storm-kafka-0.8-plus to the current Storm
incubator project.

This is the code we use in our production cluster, which has been battle
tested with billions of messages per day.

@wurstmeister @ptgoetz

I am already an Apache committer for the Mesos project, and have also previously contributed to Storm.

This is not exactly what we run in production (we're using the code from the project linked to above).