Made fix for quote characters with SmartPants + parsed literal blocks...

Made fix for quote characters with SmartPants + parsed literal blocks conditional on Sphinx version.

This hs been fixed upstream in releases >= 1.0.8 (issue 647.)

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16952 bcc190cf-cafb-0310-a4f2-bffc1f526a37