Fixed #10071 -- Changed some internal database data representations.

We now pass numbers used in data queries as actualy numbers (integers) to the
database backends, rather than string forms. This is easier for some of the
less flexible backeds.

Based on a patch from Leo Soto and Ramiro Morales.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10530 bcc190cf-cafb-0310-a4f2-bffc1f526a37