We updated highlight.min.js library to newer version (v9.12.0 -> 10.2.0) and added support for many languages. Updated extensionMap accordingly and also removed from it some unnecessary aliases, like 'json' since they are already natively supported by highlight.min.js library.
There also a new documentation page under docs/languages.md which lists all supported aliases.
* restructured JavaScript using backbone.js
* replaced highlight.js with CodeMirror for its editor
* added CodeMirror Solarized (dark) theme based on Ethan Schoonover's solarized.vim
* changed `POST /document` to accept real JSON
* cleaned up template and stylesheet