Added scalable gateway app to BUCK app list

And fixed maven artifact ID to follow the convention

Change-Id: I700c93516d4c79a3b5b93e99138a593a569e52a1
diff --git a/tools/package/BUCK b/tools/package/BUCK
index 4530576..66b0b4f 100644
--- a/tools/package/BUCK
+++ b/tools/package/BUCK
@@ -71,6 +71,7 @@
   '//apps/openstacknode:onos-apps-openstacknode-oar',
   '//apps/cpman/app:onos-apps-cpman-app-oar',
   '//apps/xosclient:onos-apps-xosclient-oar',
+  '//apps/scalablegateway:onos-apps-scalablegateway-oar',
   '//apps/events:onos-apps-events-oar',
   '//apps/test/election:onos-apps-test-election-oar',
   '//apps/test/distributed-primitives:onos-apps-test-distributed-primitives-oar',