Fix seq2seq CE (#1110)

* Seq2seq CE: do not skip the first 2 passes

fluid/neural_machine_translation/rnn_search/_ce.py

@@ -7,9 +7,9 @@ from kpi import CostKpi, DurationKpi, AccKpi
 
 #### NOTE kpi.py should shared in models in some way!!!!
 
-train_cost_kpi = CostKpi('train_cost', 0.02, actived=True)
-test_cost_kpi = CostKpi('test_cost', 0.005, actived=True)
-train_duration_kpi = DurationKpi('train_duration', 0.06, actived=True)
+train_cost_kpi = CostKpi('train_cost', 0.02, 0, actived=True)
+test_cost_kpi = CostKpi('test_cost', 0.005, 0, actived=True)
+train_duration_kpi = DurationKpi('train_duration', 0.06, 0, actived=True)
 
 tracking_kpis = [
     train_cost_kpi,