The wrapper service will "control" the services added from the
__netbox_* types to provide a general interface. This is more dynamic
than the alias approach used previously. Through this, it is possible
to handle multiple wsgi services for netbox - if this works ..
See as a reference:
http://alesnosek.com/blog/2016/12/04/controlling-a-multi-service-application-with-systemd/
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.