Implement some kind of throttling to prevent DoS

[neongreen]

See https://hackage.haskell.org/package/wai-middleware-throttle-0.2.1.0/docs/Network-Wai-Middleware-Throttle.html

[neongreen]

Have to be careful – it uses Request's remoteHost and it's always going to be 127.0.0.1. Maybe I could write my own middleware that uses the “forwarded-for” thing to replace remoteHost.