Move jetty logging off of SLF4J and onto Neo4j standard logging.

This is a first step in moving off of the extensive set of xml and properties
files governing neo4j logging, and onto programmatic runtime controls.

In this commit, jettys default SLF4J logger is replaced with an adapter that
bridges jetty logging over to Neo4j. It also translates every jetty message
such that they no longer come from the jetty-namespaced packages, but from
org.neo4j.server.web.Jetty9WebServer. This is to highlight the fact that
jetty, in this context, is an internal component of Neo4j, and that its logging
should adhere to the logging specified by the org.neo4j.* scoped logging
configuration.
I don't think this needs to be synchronized when all it does is a volatile write.