Method Metric

include/singa/model/metric.h:35–35

TODO(wangwei) call Setup using a default MetricConf.

 public:
  // TODO(wangwei) call Setup using a default MetricConf.
  Metric() = default;
  virtual ~Metric() {}
  virtual void ToDevice(std::shared_ptr<Device> device) {}
  void Setup(const string& conf) {