Migration to JavaScript / ES2015

[superbob]

Since hubotio/hubot#1347 was merged do you plan on moving to JavaScript / ES2015 also ?

CoffeeScript will still be supported, but considered as legacy in future:

Make sure that Hubot scripts can still be written in CoffeeScript. We want to break as few existing scripts as possible and many of them are written in CoffeeScript. We treat it as legacy support and will drop support for scripts written in CoffeeScript in future.
hubotio/hubot#1347

http://decaffeinate-project.org/repl/ can come in handy for an easier migration.

If you are open to pull requests I can contribute.