blog post on kafka consumers

See it formatted here:

https://github.com/johnkstockton/johnkstockton.github.com/blob/da50554191c4d1777115af275939d290aacab7d7/_posts/2013-11-30-kafka-consumers.md

What do you guys think, does this post explain enough?

I wasn't sure whether I needed to add sections explaining:
* how committing works in kafka
* what a pain it is to get it right w/ the current kafka api (barriers, stopping all threads, etc. etc.)
* how our library works

but I thought it might just make the post too long.  (Maybe that info could go in our library README?)