[UPD] Support relative path deployment

[thomaspaulb]

This supports relative path deployment using for example:

    location ~* ^/maildevel/(.*) {
      proxy_pass http://localhost:24080/$1$is_args$args;
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header Host $host;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

      # WebSocket support
      proxy_http_version 1.1;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection "upgrade";
    }

[fkantelberg]

Thank you for the contribution. It's part of the version 0.14.0. docker and pypi is deployed now.