Rewrote gatekeeper in coffee.

Major changes:
 - Rewrote source in coffeescript.
 - Changed require('express').createServer() [DEPRECATED]
 - Changed logging.

Signed-off-by: Diwank Singh <diwank.singh@gmail.com>
Edited Procfile to use coffeescript.

Other changes:
 - Updated README

Signed-off-by: Diwank Singh <diwank.singh@gmail.com>
Merge branch 'f/caffeinate'