Override etc/org.ops4j.pax.logging.cfg to generate servicemix.log in place of karaf.log

Currently, we get the etc/org.ops4j.pax.logging.cfg file coming from karaf.

This file defines a file appender that log to ${karaf.home}/data/log/karaf.log.

It can be disturbing for the users to see karaf.log and not servicemix.log.

I'm going to override the org.ops4j.pax.logging.cfg file in the assembly containing a file appender generating a servicemix.log file.