Add ocf_accounts module

This module hosts account-tools ("atool").

- nginx terminates SSL, redirects to the canonical URL, and proxies
  requests to the application server
- gunicorn runs atool
- daemontools supervises gunicorn

Future improvements:
- Deployment system; puppet is probably the wrong place to handle
  this, but it will be involved, at least in the initial checkout.
- Deploying applications and installing gunicorn in application-specific
  virtualenvs.
- Possibly switch to something besides daemontools. It seems well-suited
  for this task, but there might be alternatives that are more
  consistent with the Debian approach [1]
- Refactor slightly to better support multiple apps

This is not perfect but I'd prefer to get something in and iterate on
it, especially since atool is currently down.

Note that we switched to an accounts subdomain (instead of a
subdirectory on www) for security and ease of deployment.

[1] I did look at supervisor and some others and was not overly
    impressed, so suggestions are welcome. Maybe systemd after jessie?