[ajax] refactor/cleanup low-level ajax functions * loadxhtml/replacePageChunck/reload_component/reload_box deprecated in favor of loadXHTML / ajaxFuncArgs * some other cleanups in cubicweb.ajax.js * add js_render which will replace js_component (more generic, nicer argument passing handling)

bgcolor = '#000000'
stylesheets = ['%s/cubicweb.css' % datadir_url]
logo = '%s/logo.png' % datadir_url