Moved clean_club_app_link_id to cleaning.
This method is now also used by the club create_form. Which means that you cannot create a new club with an already reserved link_id until the club application has been rejected.
Patch by: Lennard de Rijk
Reviewed by: to-be-reviewed
"""
>>> from django.contrib.sites.models import Site
>>> from django.conf import settings
>>> Site(id=settings.SITE_ID, domain="example.com", name="example.com").save()
>>> # Make sure that get_current() does not return a deleted Site object.
>>> s = Site.objects.get_current()
>>> isinstance(s, Site)
True
>>> s.delete()
>>> Site.objects.get_current()
Traceback (most recent call last):
...
DoesNotExist: Site matching query does not exist.
"""