Support tmda-cgi running as a full WSGI app

[pjz]

CGI is kind of out of favor; better would be to have a way to stand up tmda-cgi (may need renaming!) as its own webapp on its own port so it can be reverse-proxied or run on a loopback or whatever. So we should either:

1. change it to a WSGI app
2. write a teeny server that does nothing but run the single CGI.