Optimize logging bridge

[Former user]

According to the official Restlet site, it's faster to use Slf4jLoggerFacade (in "org.restlet.ext.slf4j.jar") than SLF4JBridgeHandler.

Source (end of page) : http://wiki.restlet.org/docs_2.0/13-restlet/275-restlet/311-restlet/101-restlet.html

PS: if you add this jar, I will be able to use it in the WebUI ;-)

[Petr Nejedly]

done as a part of the Restlet upgrade