Lesson Builder hardcodes the "default" skin in several places

In most or all RSF templates, and one JSP file (tool/src/webapp/removePage.jsp), there are hardcoded references to /library/skin/default/tool.css and /library/skin/default/portal.css. Since the skin may be changed, and since, in 2.9, "default" is no longer even the default skin, these templates should instead respect the skin chosen by administrators and site owners and provided via the portal as described in https://source.sakaiproject.org/svn//reference/trunk/docs/architecture/sakai_tool.doc (line 300).