call rhn-config-satellite.pl only if anything has changed

fixing
2014-06-18 08:23:14,917 [TP-Processor10] ERROR com.redhat.rhn.manager.satellite.SystemCommandExecutor - Error encountered executing (args=[/usr/bin/sudo, /usr/bin/rhn-config-satellite.pl, --target=/etc/rhn/rhn.conf, 2>&1, >, /dev/null])
2014-06-18 08:23:14,918 [TP-Processor10] ERROR com.redhat.rhn.manager.satellite.SystemCommandExecutor - Error message from process: usage: /usr/bin/rhn-config-satellite.pl --target=<target_file> --option=<key,value> [ --option=<key,value> ] [ --help ]
Automatic commit of package [spacewalk-java] release [2.2.117-1].