move app/assets/javascripts/lib/utils/ to app/assets/javascripts/commons/

$ ls app/assets/javascripts/commons/
bootstrap.js    index.js    jquery.js    polyfills    polyfills.js    vue.js
$ ls app/assets/javascripts/lib/
ace    ace.js    utils

• lib/utils/ should be in commons/
• current stuff in commons/ should live with ace.js in lib/
• lib/ace.js should be replaced by node module

(related question in Slack https://gitlab.slack.com/archives/C0GQHHPGW/p1507110104000330)