If syslog_aggregator running, properties host/port required

If syslog_aggregator job template is running then deployment
file should provide:

    properties:
      syslog_aggregator:
        host: 0.syslog_aggregator.default.mydeployment.bosh
        port: 54321

If syslog_aggregator job template is not running, then
do not specify `properties.syslog_aggregator` at all.