[1.2.X] Fixed #14235 - UnicodeDecodeError in CSRF middleware

  
Thanks to jbg for the report.
  
This changeset essentially backs out [13698] in favour of a method that
sanitizes the token rather than escaping it.

Backport of [13732] from trunk.




git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@13733 bcc190cf-cafb-0310-a4f2-bffc1f526a37