Fixed #10034: the formtools security hash function is now friendlier to...

Fixed #10034: the formtools security hash function is now friendlier to browsers that submit leading/trailing whitespace in form fields.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10752 bcc190cf-cafb-0310-a4f2-bffc1f526a37