Implement L2 load balancing service

Including event/listener, CLI support

Change-Id: I26f1da578a72f5b3ead413aa5155233fbf9ab2b6
diff --git a/modules.bzl b/modules.bzl
index 837ecd0..fa2e82d 100644
--- a/modules.bzl
+++ b/modules.bzl
@@ -164,6 +164,7 @@
     "//apps/flowanalyzer:onos-apps-flowanalyzer-oar",
     "//apps/intentsync:onos-apps-intentsync-oar",
     "//apps/influxdbmetrics:onos-apps-influxdbmetrics-oar",
+    "//apps/l2lb:onos-apps-l2lb-oar",
     "//apps/metrics:onos-apps-metrics-oar",
     "//apps/mfwd:onos-apps-mfwd-oar",
     "//apps/mlb:onos-apps-mlb-oar",