Chapter Prose

First draft of the chapter prose, in rst form for now. I'm requesting PR to have someone look at the prose. I've also included an svg diagram, but you'll have to pull the repository to see it. I don't think it's viewable within github...

If you want to pull this, this is the 'chapter' branch from https://github.com/malini/500lines
At this point in the chapter I still don't feel as though I have a good grasp on the architectural drivers of the project. Why use threading over an event driven model? I'm sure there is a reason I just don't feel like the writing has adequately explained the architecture driving the details we have dived into here (TCP/threading/etc.)