Update highlight.js to 8.1

Also added support for less common languages. All languages from
http://highlightjs.org/download/ now supported

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'update-highlight-js' into 'master'

Update highlight.js to 8.1

Pack version including all supported languages. Yay for Haml, Clojure, Go and Erlang support!

Fixes #1411.

See merge request !956