Vendor the css and refer to it instead

We were linking to `http://jashkenas.github.io/docco/resources/linear/docco.css` but that has changed a lot and the examples all look horrible now.  This should fix it.
I think what I'm going to do here is calculate the relative path of the example to the css file. We know where the css file is and we know the path to the file, so we can count the slashes and put the right amount of '../' in a string to pass to mustache.