fix #632 IO.swf not loaded when Aria.rootFolderPath is changed

1) When I do sth like this in my code:

    Aria.rootFolderPath = "http://example.org/here/is/my/stuff/";
    aria.core.DownloadMgr.updateRootMap({"aria": {"*" : "http://example.org/here/is/aria-templates/"}});

then IO.swf will be mistakenly loaded from `here/is/my/stuff` instead of from `here/is/aria-templates/`.

This commit fixes that issue.

2) Having the above rules applied, when I make a call like this:

                Aria.loadTemplate({
                    classpath:'testClassPath.Test',
                    div:"main",
                    moduleCtrl : {
                        classpath : "testClassPath.Controller"
                    }
                });

(both paths pointing to physical files not conforming same-origin), then only one of those files was actually requested due to a bug in `XDR.js`.