So perhaps it is impossible for anyone to approach the payment server from
these other domains now.

Mostly though I want to force CI to run because whetstone is not currently
showing the pipeline status for this MR...

Copy everything from how the issuer does it.

Just require hostName and domain instead of an extra publicIPv4 option.  Leave
behind a similar option, `publicAddress`, just in case it needs to be
overridden at some point, but stop supplying a value for it anywhere.

More flexibility and less dots in config files.
Implements #65.

Also configure a new value on the staging grid

Also put library code in a library directory