Add protocol support to the ES config info in apiman.properties

apiman-manager.storage.type=es
apiman-manager.storage.es.host=${apiman.es.host}
apiman-manager.storage.es.port=${apiman.es.port}
apiman-manager.storage.es.cluster-name=${apiman.es.cluster-name}
apiman-manager.storage.es.initialize=true

apiman-manager.storage.es.protocol=${apiman.es.protocol}