Update the voltha code to make use of the interface option and add
a new voltha swarm file.

Change-Id: Icf2bd5a35aea3a8aa55de58acb56bfa6f4b34e0d
diff --git a/compose/docker-compose-voltha-swarm.yml b/compose/docker-compose-voltha-swarm.yml
new file mode 100644
index 0000000..39532f7
--- /dev/null
+++ b/compose/docker-compose-voltha-swarm.yml
@@ -0,0 +1,30 @@
+version: "3"
+services:
+  voltha:
+    image: cord/voltha:latest
+    deploy:
+      replicas: 3
+    entrypoint:
+      - voltha/voltha/main.py
+      - -v
+      - --consul=consul:8500
+      - --fluentd=fluentd:24224
+      - --kafka=kafka
+      - --rest-port=8880
+      - --grpc-port=50555
+      - --instance-id-is-container-name
+      - --interface=eth2
+      - --backend=consul
+    networks:
+      - net
+    ports:
+      - "8880:8880"
+      - "18880:18880"
+      - "50555:50555"
+    volumes:
+      - /var/run/docker.sock:/tmp/docker.sock
+
+networks:
+  net:
+    external:
+      name: voltha_net