Add Procfile
Add Procfile

The Procfile is how we'll run the application on GOV.UK infrastructure.

It uses config values that are currently set in /etc/gds/stagecraft/gunicorn
on Performance Platform machines, but moving those values into the Procfile
is the easiest way to get the application up and running.

alphagov/stagecraft,alphagov/stagecraft,alphagov/stagecraft,alphagov/stagecraft