* Service time expiry

- Replies include "this service expires on".

* Add real Unit Testing.

- Spec out the system through test harnesses.  If the tests can run
   the system, it's complete.

- Differentiate backends and the independent system.

* Message Queuing

- Process a maximum of X MB over Y requests per unit time Z per
   friend.

- Messages that exceed that maximum are queued for the next time unit.

* Process Separation

- Listeners aren't senders aren't controllers.

* Actual PGP sig verification.

* Send replies to the recipient's Santiago.

- Queue the Santiagi and wait for a reply.  If we time out before
   receiving a reply, go on to the next Santiago.

* Move Santiago data store to James's databases.

* Implement real Santiago request/reply/response.

- Need to move to James's database first.
