Fixed #8904 -- Improved error message when spatial lookup is not available,...

Fixed #8904 -- Improved error message when spatial lookup is not available, and changed exception to `ValueError` to prevent swallowing of error on queryset evaluation.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@12887 bcc190cf-cafb-0310-a4f2-bffc1f526a37