Add BertJapaneseTokenizer as tokenizer_class

config.json

@@ -15,6 +15,7 @@
   "num_attention_heads": 4,
   "num_hidden_layers": 12,
   "pad_token_id": 0,
+  "tokenizer_class": "BertJapaneseTokenizer",
   "position_embedding_type": "absolute",
   "summary_activation": "gelu",
   "summary_last_dropout": 0.1,