If a business template contains skin folder which registers a new skin make sure that when this skin folder is uninstalled
the skin is removed from portal_skins tool. 
This way both install/uninstall process is consistent with respect to skin handling. 


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@24710 20353a03-c40f-0410-a6d1-a30d3c3de9de