Issue/30 content encoding

[snuggs]

Fixes #30

In the long term is best to have a setup with nginx, http/2 etc. However can just use app server for time being.

Content Negotiation

File types determinant on accept header.

• [ ] Use koa-send for distribution libraries - https://github.com/koajs/send (Particularly for these lines)
• [ ] Use koa-static for all other static assets.

[snuggs]

@brandondees @tmornini @RobertChristopher using Content Negotiation to determine if request Accept header is a script or not. If so then root returns script file. If brotli available returns *.br otherwise gracefully degrades to *.gz.

Will associate domain name so "Installation" will be merely <script src=//snuggsi.es></script>