Load highlight.js via npm instead of off of a cdn

[halfwit]

Ideally we should be loading these dependencies via npm so we can self host them instead of using a 3rd party.

npm dependencies are currently defined here -
https://github.com/wetfish/classic/blob/master/wiki/src/package.json

and there are symlinks to the node_modules folder
https://github.com/wetfish/classic/tree/master/wiki/src/js

Originally posted by @itsrachelfish in #44 (comment)