Move document sidebar entries extraction to document.View
This way other modules can benefit from the same logic. Also make use
of the sidebar.getSidebarMenu method so that getMenusForScope is no
longer specific to full menu's.
Patch by: Sverre Rabbelier
"""
>>> 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.
"""