Vert.x 3 GW: Fix JSON format

  "registry": {
    "class": "io.apiman.gateway.engine.es.ESRegistry",
    "config": {
      "client.type": "jest",
      "client.cluster-name": "elasticsearch_msavy",
      "client.host": "localhost",
      "client.port": "9201"
    }
  },

"registry": {
  "class": "io.apiman.gateway.engine.es.ESRegistry",
  "config": {
    "client" : { 
        "type": "jest",
        "cluster-name": "elasticsearch_msavy",
        "host": "localhost",
        "port": "9201"
    }
  }
}