Create artifact providing set of log4j Markers for filtering logs in unified way

Log4j provides the option to specify marker for each individual log entry. The behaviour of these Markers can be specified in log4j config file. There is a lot what log4j can do to marked entries: hide from all and-or selected loggers, forward, encrypt, reformat etc.

Since the log4j config file is located in odlparent/karaf/opendaylight-karaf-resources/src/main/resources/etc/org.ops4j.pax.logging.cfg it is only logical to create odlparent artifact which will provide the Markers to all child ODL projects so the marking is consistent.