WIP: add compatibility for Coffeescript 2

[mistydemeo]

Summary

This PR starts the work on making sure the classes in this code work in Coffeescript 2. As mentioned previously, a few of the semantic differences between Coffeescript 1 classes and ES2015 classes has introduced some backwards compatibility issues, documented here: https://coffeescript.org/#breaking-changes

Currently, this mostly works, but trying to actually launch Hubot fails with a TypeError: Cannot read property 'bind' of undefined error. I believe this may be because of the following:

ES2015 classes don’t allow bound (fat arrow) methods. The CoffeeScript compiler goes through some contortions to preserve support for them, but one thing that can’t be accommodated is calling a bound method before it is bound

refs #526.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[CLAassistant]

All committers have signed the CLA.

[seratch]

Let me close this as #565 has been merged into master branch