stack/cloudooo: Drop stunnel.

Nothing uses it in this software release.

stack/cloudooo.cfg

@@ -25,7 +25,6 @@ extends =
   ../component/poppler/buildout.cfg
   ../component/python-2.7/buildout.cfg
   ../component/rdiff-backup/buildout.cfg
-  ../component/stunnel/buildout.cfg
   ../component/xorg/buildout.cfg
 
 versions = versions
@@ -36,7 +35,6 @@ parts =
 [stack-cloudooo-buildout]
 parts =
   libreoffice-bin
-  stunnel
   dcron
   install-plone-recipe-command