download karaf 4.2.1 from maven central

Change-Id: Icb7e0400ee5b34ed4be33afdda5074a6f6ec1f6d
diff --git a/tools/package/bin/onos-restore b/tools/package/bin/onos-restore
index b7204e5..b6bc4bc 100755
--- a/tools/package/bin/onos-restore
+++ b/tools/package/bin/onos-restore
@@ -5,7 +5,7 @@
 
 ONOS_HOME=${ONOS_HOME:-$(cd $(dirname $0)/.. >/dev/null 2>&1 && pwd)}
 ONOS_DEFAULT_ARCHIVE=$(dirname $ONOS_HOME)/onos-data.tar.gz
-ONOS_KARAF=$ONOS_HOME/apache-karaf-3.0.8
+ONOS_KARAF=$ONOS_HOME/apache-karaf-4.2.1
 
 # Fetch the name of the archive or use a default if none is specified
 archive=${1:-$ONOS_DEFAULT_ARCHIVE}