Brown-paper-bag commit. This is what happens when one pays more attention to CMF 1.5 compatibility than to CMF 2.x compatibility one is trying to achieve. Make the skin registration also work on CMF 2.x as well (approved by jerome)

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@29615 20353a03-c40f-0410-a6d1-a30d3c3de9de