Fix logging setup _ Silence message about missing SLF4J implementation _ Route java.util.logging to Log4J (at least restlet is affected) _ Let messages of additional loggers pass to the root loggers appender (otherwise, they don't appear at all)

<Context>
    <!-- Override context parameters in web.xml of gwt-client deployment here.
         E.g. uncomment the following to use SSO via GGinA: -->
    <!-- <Parameter name="authentication" value="ggina" override="false"/> -->
</Context>