Simplify optional member services and their checkboxes

[raimom]

There's unnecessary complexity with the optional member serivces and their checkboxes in the member application form.
The following:

Jäsenpalvelut
[] Vuosimaksu, 30€ / vuosi
[] Tilankäyttöoikeus, 40€ (10€ min) / kuukausi
Valitse, jos haluat ympärivuorokautisen pääsyn

The two check boxes are probably two too many options in at least 80% or maybe even more than 90% of the new member application cases. It is probable that practically all of the new member applications want the access so it should be default.

The suggestion is to remove the check boxes and set the access fee variable on and create the reference number as default.

[braaar]

Could it be useful to let this form be configurable via the admin panel in some way? Since #433 that is quite easy to set up