What about stylesheets?

This was originally part of shawnbot/swagger-static#1, but I'm moving it here for safe keeping.

Here are some options for distributing stylesheets:

1. Just bundle a stylesheet with swagger-template and let people copy it as needed.

2. Make a CDN-hosted default stylesheet and reference that in the swagger-template.

3. Ignore styling altogether and let users specify stylesheets in a custom template, as in:

   {% extend "swagger.html" %}
   {% block css %}
   <link rel="stylesheet" href="path/to/custom.css">
   {% endblock %}