Fixed #9942 -- Added a to_python handler for FloatField to ensure correct typing of deserialized data before saving. Underlying problem is analogous to #8298, fixed in [8515]. Thanks to David Larlet <larlet@gmail.com> for the report and fix.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9695 bcc190cf-cafb-0310-a4f2-bffc1f526a37