x509 certificate management

[buhman]

9GBz shows a serious oversight in namespace.

ptpb currently serves a certificate with common name: ptpb.pw, when clients connect to ptpb with a different domain name, certificate validation fails, as the certificate common name doesn't match.

pb should probably support associating x509 certificate keypairs with namespaces. However, because nginx is currently terminating SSL on ptpb.pw, a implementation that involves directly manipulating nginx configuration would be scary.

Such abuse.