Docs WIP

@jrolfs @cantino 

First pass at some docs just to get the ball rolling.  I made use of [codo](https://github.com/coffeedoc/codo), which generates documentation from inline comments.  Codo is a command-line tool installed by ```npm install -g codo```.  Once installed, run ```codo``` from the root project folder to dump all the docs into ```/doc```.  I picked Codo because it has some great support for coffeescript specific features like mixins.  It also has some first class support for defining ```options``` objects.

I pushed a generated copy of the docs to this repo's ```gh-pages``` branch, so you can see the docs I completed right now [here](http://mavenlink.github.io/brainstem-js/doc/).  Only ```Brainstem.Model``` and ```Brainstem.Collection``` have any progress right now, except for ```fetch``` on each one. 

Thoughts?