WIP: Initial implementation of Podder

Podder is a service which monitors consul registered services
in order to spin up their dependencies. Dependencies are
indicated as SERVICE_x_TAGS as a csv. Podder picks those
dependencies up and spins up specified containers in their own
network. For example, if a voltha_1 is instantiated
podder will spin up chameleon_1 and ofagent_1.

Change-Id: I0c1add8530c78fc761e39fe58cf24f14e96c0ba4
diff --git a/compose/docker-compose-system-test.yml b/compose/docker-compose-system-test.yml
index a3e8ab1..3ef7b03 100644
--- a/compose/docker-compose-system-test.yml
+++ b/compose/docker-compose-system-test.yml
@@ -97,6 +97,7 @@
       SERVICE_8880_CHECK_INTERVAL: "5s"
       SERVICE_8880_CHECK_TIMEOUT: "1s"
       SERVICE_50555_NAME: "voltha-grpc"
+      SERVICE_50555_TAGS: "chameleon,ofagent"
     volumes:
     - "/var/run/docker.sock:/tmp/docker.sock"
   #