Bong-Min Kim

Results 2 issues of Bong-Min Kim

`loss_fct(logits.view(-1, self.num_labels), labels.view(-1))` and `loss_fct(logits, labels)` do the same thing, the latter code is more efficient.

중복하여 불러지는 `sklearn.metrics.f1_score` 메소드를 `from sklearn.metrics import f1_score as skl_f1_score`로 한 번만 import 하게 수정하였습니다.