Added scalable gateway app to BUCK app list

And fixed maven artifact ID to follow the convention

Change-Id: I700c93516d4c79a3b5b93e99138a593a569e52a1
diff --git a/BUCK b/BUCK
index d70c52b..2573600 100644
--- a/BUCK
+++ b/BUCK
@@ -142,6 +142,7 @@
     '//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',
 ]
 
 APP_JARS = [