fix jetty log versions and deps

I've removed the slf4j-simple lib which was quite old and definitely not necessary (since jetty can use commons-logging + log4j).
Changed the <scope>provided</scope> which actually didn't works (we have commons-loggin-1.0.jar into di lib) into and exclusion so now we have in the shared jetty lib folder:
commons-logging-1.1.1.jar
log4j-1.12.14.jar
... (others not related to log)...