use websockets for updating
use websockets for updating

This piggy backs off of two examples:
  - https://github.com/gorilla/websocket/blob/master/examples/filewatch/main.go
  - https://github.com/fsnotify/fsnotify/blob/master/example_test.go

This also uses the Github CSS, as scraped and hosted from:
  - https://github.com/sindresorhus/github-markdown-css
  - https://rawgit.com/

henrywallace/mdpreview,henrywallace/mdpreview,henrywallace/mdpreview,henrywallace/mdpreview