MetricsConsumer handle recursive values, fixes #550 and #526

[jnioche]

No description provided.

[jnioche]

the metric which was causing the issue is now processed succesfully

   {
        "_index" : "metrics",
        "_type" : "datapoint",
        "_id" : "KNjRbGIBsMxvwQvn1h04",
        "_score" : 1.0,
        "_source" : {
          "srcComponentId" : "__system",
          "srcTaskId" : -1,
          "srcWorkerHost" : "localhost",
          "srcWorkerPort" : 6700,
          "name" : "__recv-iconnection.dequeuedMessages",
          "value" : 0.0,
          "timestamp" : "2018-03-28T13:35:13.975Z"
        }
      }