Explicitly set healthcheck command.

We were setting them in the Dockerfile's previously.  However this
caused the healtcheck commands to always run regardless of which
process we were running in the container.  This caused 'unhealthy'
containers at times they were never intended to be checked.  This
change makes it so they are explicitly set.

Change-Id: I7bc12d236b3cc7a52d3e6aa706fd04675dad3a9a

docker/services/opendaylight-api.yaml

@@ -93,6 +93,8 @@ outputs:
             detach: true
             user: odl
             restart: always
+            healthcheck:
+              test: /openstack/healthcheck
             volumes:
               list_concat:
                 - {get_attr: [ContainersCommon, volumes]}
@@ -116,4 +118,4 @@ outputs:
       upgrade_tasks:
         - name: Stop and disable opendaylight_api service
           tags: step2
-          service: name=opendaylight state=stopped enabled=no
+          service: name=opendaylight state=stopped enabled=no