title: Transformers errors (encoding errors) when trying to finetune FlauBERT
body: <p>I am doing a  binary classification task. It consists in classifying Amazon reviews. I am using FlauBERT( french version of BERT) for language modelling in order to produce my vectors. So Following the steps provide in github, I try to finetune FlauBERT on my task using the library "transformers" of hugging face but I am encountering this error and I cannot seems to find the solution. I read others post on it but so far, everything I tried failed. I checked the encodage of the data I used and they are encode in "utf-8". I change the encodage when reading the files to cp1252 but still sames answer. Apperently the problem lies with my data but I can seem to figure out how to overcame this error.</p>
  
  <pre><code>Traceback (most recent call last):
    File "transformers/examples/run_flue.py", line 782, in &lt;module&gt;
      main()
    File "transformers/examples/run_flue.py", line 737, in main
      cache_dir=args.cache_dir if args.cache_dir else None,
    File "/home/anaconda3/envs/env/lib/python3.6/site-packages/transformers/configuration_utils.py", line 188, in from_pretrained
      config_dict, kwargs = cls.get_config_dict(pretrained_model_name_or_path, **kwargs)
    File "/home/anaconda3/envs/env/lib/python3.6/site-packages/transformers/configuration_utils.py", line 240, in get_config_dict
      config_dict = cls._dict_from_json_file(resolved_config_file)
    File "/home/anaconda3/envs/env/lib/python3.6/site-packages/transformers/configuration_utils.py", line 329, in _dict_from_json_file
      text = reader.read()
    File "/home/anaconda3/envs/env/lib/python3.6/codecs.py", line 321, in decode
      (result, consumed) = self._buffer_decode(data, self.errors, final)
  UnicodeDecodeError: 'utf-8' codec can't decode byte 0x80 in position 0: invalid start byte
  
  
  </code></pre>