Fixed namespace of atom feed XHTML summary
* all xhtml elements contained a empty xmlns attribute
** this was fixed through a custom "xhtml_copy" mode template
Changed base url and url scheme
* base url is now a local webserver for more realistic testing
** i.e. otherwise the atom feed is not served correctly
* article, page, tag and stream pages are now generated as "index.html" inside appropriately named directories
** this is needed for pretty urls that actually work