add missing highlight language

Author: hauner

src/js/vendor/highlight.bundle.js

@@ -26,7 +26,7 @@
   // hljs.registerLanguage('objectivec', require('highlight.js/lib/languages/objectivec'))
   // hljs.registerLanguage('perl', require('highlight.js/lib/languages/perl'))
   // hljs.registerLanguage('php', require('highlight.js/lib/languages/php'))
-  // hljs.registerLanguage('properties', require('highlight.js/lib/languages/properties'))
+  hljs.registerLanguage('properties', require('highlight.js/lib/languages/properties'))
   // hljs.registerLanguage('puppet', require('highlight.js/lib/languages/puppet'))
   // hljs.registerLanguage('python', require('highlight.js/lib/languages/python'))
   // hljs.registerLanguage('ruby', require('highlight.js/lib/languages/ruby'))