Added zipkin to docker compose

Author: pioardi

docker/docker-compose-swarm.yml

@@ -101,3 +101,8 @@ services:
     image: cassandra:3.0
     ports:
       - "9042:9042"
+#https://github.com/openzipkin/docker-zipkin
+  zipkin:
+    image: openzipkin/zipkin:2
+    ports:
+      - "9411:9411"