Fixed #8298: Added a to_python method for integer fields. This ensures that...

Fixed #8298: Added a to_python method for integer fields. This ensures that the data from deserialized instances is of correct type prior to saving. Thanks to Andrew Badr for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8515 bcc190cf-cafb-0310-a4f2-bffc1f526a37