Made the semi-private _max_form_count live on the public API of formsets by...

Made the semi-private _max_form_count live on the public API of formsets by renaming it to max_num. This also removes the ManagementForm use of MAX_COUNT since that usage should just be referenced to the formset's max_num property. Refs #7899. Thanks Peter of the Norse for straightening me out.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8058 bcc190cf-cafb-0310-a4f2-bffc1f526a37