moves sortable JS code from DesignerManager category list template to jquery.cms_admin as cms_initSortable(table, actionurl) function so it can be reused in other places

git-svn-id: http://svn.cmsmadesimple.org/svn/cmsmadesimple@8832 3d254a34-79dc-0310-9e5f-be208747d8a0