Declare netty.version and reuse it in commons pom.
Declare netty.version and reuse it in commons pom.

Change-Id: Idf1dc5a7ac172583dd2171fa73c13367a0af5637
Signed-off-by: Alissa Bonas <fb6f204bea4868e5fad08a7576b6b090e7fa2b20@redhat.com>

tx1103mark/controller,opendaylight/controller,mandeepdhami/controller,aryantaheri/monitoring-controller,inocybe/odl-controller,inocybe/odl-controller,aryantaheri/monitoring-controller,mandeepdhami/controller,Sushma7785/OpenDayLight-Load-Balancer,violinlakshmi/opendaylight,mandeepdhami/controller,violinlakshmi/opendaylight,my76128/controller,aryantaheri/controller,my76128/controller,aryantaheri/controller,tx1103mark/controller,aryantaheri/monitoring-controller,aryantaheri/monitoring-controller,Johnson-Chou/test,tx1103mark/controller,violinlakshmi/opendaylight,mandeepdhami/controller,Sushma7785/OpenDayLight-Load-Balancer,my76128/controller,my76128/controller,522986491/controller,Johnson-Chou/test,tx1103mark/controller,aryantaheri/controller,522986491/controller