Execute bin without coffeescript

[arthurTemporim]

This PR is about issue #1 .

I removed coffeescript from package.json and run some tests and everything works fine. In this gif i've recorded the result. The @rocket.chat/sdk was required and i updated the hubot-rocketchat adpter to the version 2.0.0 published at npm.
I added the gif to README.md too.

Have other way to verify if coffeescript was removed and have no issues?

[timkinnane]

@arthurTemporim Nice work Arthur. Couple follow ups...

@rocket.chat/sdk shouldn't be required, it's already a dependency of the adapter. The modules can be accessed like robot.adapter.driver in the latest version, but that one hasn't been published yet.

#1 was mostly related to the bin/hubot way of running the bot, used in a lot of services like Heroku. The bin script launches from the main Hubot binary in node_modules and according to that, coffee script is still required. See https://github.com/hubotio/hubot/blob/master/bin/hubot

You could try using bin/hubot to run the bot from your command line without coffee script. It might get it from the dependency. I haven't done a lot of testing.