Disable default JUL configuration when using the SLF4J bridge

SLING-2193 added support to redirect JUL logging messages over to SLF4J logging.

The drawback of the solution is that there is still default configuration read from the JVM platform $JAVA_HOME/lib/logging.properties which causes the JUL ConsoleHandler to be installed.

Under the assumption that on startup no special logging configuration file is specified with the "java.util.logging.config.file" system property and no logging configuration class is configured with the "java.util.logging.config.class" system property, we should provide a custom configuration class, which does nothing but prevents default configuration from being read.