The Gunicorn type now supports systemd sockets only. With uWSGI, you can
choose between it and the native sockets based on the parameters chosen.
This is done because it could not be implemented to have multiple
protocols with the systemd sockets (so you may choose).
The systemd socket unit file is generally available, so both types use
the same script to generate the socket unit file.
Because someone *want* to use something other than just gunicorn, it was
extracted to a own type. Because gunicorn is a bit deep in the netbox
installation process, it's a bit harder to isolate it.
`__netbox_uwsgi` will come, too.
matze