Fix/no jetty logs in console

 Avoid jetty logging in karaf shell.

From commit 0dfdd27 message:

There is an issue with jetty server logging in karaf:
From https://issues.apache.org/jira/browse/KARAF-1117

To avoid it following workarround can be applied:
Define following property in system.properties file:
Workaround for KARAF-1117: Jetty will use a JUL logger.
org.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.JavaUtilLog

This workaround should be removed when using jetty 7.6.3 or above, as it will include a proper fix.

This patch applies this workarround in opennaas platform.
To do it, a copy of karaf-2.2.2-fuse-04-06 system.properties has been added to platform /etc,
and the workarround has been aplied to it.

IMPORTANT NOTICE:
Any karaf upgrade made in the future should take into account that this system.proeprties file may become out of date.
Being that the case, it should be replaced by the new one and the workarround applied again.