Add CoffeeScript support

* Use [CoffeeLint] to keep to a community-supported open source standard.
* Roll out CoffeeScript to certain GitHub orgs.
* Memoize the HTTP requests.

[CoffeeLint]: http://www.coffeelint.org/
Add flag to enable CoffeeScript

* rename `Null` style guide to `Unsupported`
Handle error where Services team already exists

Error reference:
https://app.getsentry.com/app20126465herokucom/production/group/18233199
Clean up GithubApi tests

* add a test to catch the validation error on team creation scenario