[1.2.X] Converted contrib/auth/tokens doctests to unittests. We've always said "no more" to doctests.

      Backport of [14100] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14102 bcc190cf-cafb-0310-a4f2-bffc1f526a37