Removed port argument from Robot constructor

I continue to simplifier the codebase. This change removes the port argument from Robot and moves the ability to set the port number to the setupExpress method.

Refactor Middleware execution signature

• Simplified the Middleware callback signature, callback just includes a Response instance.
• Refactored tests to use Nodes Test Runner (TAP)

Enable ability to build a website with Hubot

Return the Express JS app instance so that you can "do what you want" with it.

Added CatchAll facility back in

I removed the CatchAll functionality in a previous version. Adding it back in.
Also removed some build and publish dependencies because I don't think this will be published to NPM.

Move to ES6 programming style

This release modernizes the codebase to utilize ES6 programming style including async/await.

It definitely contains breaking changes from the 3.x version of Hubot.