I've actually not used awsbox much -- @lloyd, could you chime in? This is only used to tell Google's OpenID endpoint where to return users. This will be `https://google.login.persona.org` in production, and will have multiple boxes behind a load balancer.

We'll want to do the same thing at some point when testing: stand up 2-3 awsboxen behind a round robin load balancer, and they'll all set this to the same value.