Split classes into separate files (a.k.a. The Big Split).

This has been a while coming, so better get it out of the way now.

For those interested, almost all of the core code has been living in
`lib/jamie.rb`/`lib/kitchen.rb` since the beginning. This was one of
many experiments I tried when working up the codebase. Why would I do
this?

* the code was very fast to navigate (use editor buffer search)
* refactoring was super easy as almost all the code is right there
* it kept scope/code creep in check (the line count is constantly in
* your face)
* ordering of classes and modules could be arranged in a way that made
* reading the code base more logical (higher order objects could be
* presented first with internal details pushed further down)

---

It was fun for me while it lasted but as `lib/kitchen.rb` grew over 1500
lines a lot of these benefits broke down. If you want to track code base
size (code line count, comment line count, etc.) just run `rake stats`.
It's running at the end of the default Rake task to keep everyone
honest, honest.

Closes #39
Merge branch 'split-core-to-files' into 1.0