Pass iteration_number to metrics.log_metric as keyword argument. Fix …

…bug where it was being passed to the timestamp positional argument. (#62)

Overriding CI fail due to urgency and clear fix.

smdebug/core/hook.py

@@ -569,7 +569,8 @@ def _write_scalars(self):
             write_tb = scalar_obj.write_tb
             write_event = scalar_obj.write_event
             if self.metrics_writer and sm_metric:
-                self.metrics_writer.log_metric(scalar_name, scalar_val, self.mode_steps[self.mode])
+                self.metrics_writer.log_metric(scalar_name, scalar_val,
+                                               iteration_number=self.mode_steps[self.mode])
             if write_tb:
                 tb_writer = self._maybe_get_tb_writer()
                 if tb_writer: