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

app/assets/javascripts/application.js.coffee

@@ -23,7 +23,7 @@
 #= require g.raphael-min
 #= require g.bar-min
 #= require branch-graph
-#= require highlightjs.min
+#= require highlight.pack
 #= require ace/ace
 #= require d3
 #= require underscore