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
The chapter feels as though it finally starts to develop narrative flow here near the end of the chapter. I think earlier portions of the chapter could benefit from the same sort of narrative that is found here. Some of the earlier sections feel as though someone is working their way through the code and just translating what is happening, rather than explaining it (This happens and then this happens and then....). After reading the chapter I understand approximately how I might build a CI system, but I don't feel as though I have a strong argument/good reasoning behind the decisions that were made.