Adding GUI 2 as a default to be activated if ONOS_APPS is unspecified.

Change-Id: I386b54bfb732e8b176129e72caa4093ed51866b7
diff --git a/tools/package/bin/onos-service b/tools/package/bin/onos-service
index cac0031..d2879ef 100755
--- a/tools/package/bin/onos-service
+++ b/tools/package/bin/onos-service
@@ -21,7 +21,7 @@
 ONOS_HOME=${ONOS_HOME:-$(cd $(dirname $0)/.. >/dev/null 2>&1 && pwd)}
 KARAF_ARGS=server
 SYS_APPS=drivers
-ONOS_APPS=${ONOS_APPS:-}  # Empty means don't activate any new apps
+ONOS_APPS=${ONOS_APPS:-gui2}  # Activate GUI2 unless specific apps were named
 
 cd $ONOS_HOME