message: Query Browser: Display "{}" when a data series has no labels
  Avoids having a blank "Series" column.
diff: @@ -937,7 +937,9 @@ const MetricsList = ({metrics}) => <div className="co-m-table-grid co-m-table-gr
  <div className="col-xs-9 query-browser-metric__wrapper">
  <div className="query-browser-metric__color" style={{backgroundColor: graphColors[parseInt(i, 10) % graphColors.length]}}></div>
  <div className="query-browser-metric__labels">
  - {_.map(m.labels, (v, k) => `${k}="${v}"`).join(',')}
  + {_.isEmpty(m.labels)
  + ? <span className="text-muted">{'{}'}</span>
  + : _.map(m.labels, (v, k) => `${k}="${v}"`).join(',')}
  </div>
  </div>
  <div className="col-xs-3">{m.value}</div>
  