Fixed #16677 -- Fixed the future version of the ssi template tag to work with template file names that contain spaces. Note that this fix cannot be applied to the currently deprecated version of the ssi tag since it requires an unquoted literal as parameter. Many thanks to Aymeric Augustin for the report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16687 bcc190cf-cafb-0310-a4f2-bffc1f526a37