[1.0.X] Fixed #9473: FormWizard now works with NullBooleanFields. As a bonus,...

[1.0.X] Fixed #9473: FormWizard now works with NullBooleanFields. As a bonus, we now have the beginnings of a test suite for FormWizard. Thanks, Keith Bussell. Backport of r10316 and r10319 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10321 bcc190cf-cafb-0310-a4f2-bffc1f526a37