AutoModel fails to load FlauBERT with `output_hidden_states`
MWE:

```python
import transformers

model = transformers.AutoModel.from_pretrained("flaubert-base-cased", output_hidden_states=True)
```

Tested on rev 5a6b138 fails with

```console
Traceback (most recent call last):
  File "mwe.py", line 3, in <module>
    model = transformers.AutoModel.from_pretrained("flaubert-base-cased", output_hidden_states=True)
  File "<redacted>/transformers/modeling_auto.py", line 377, in from_pretrained
    return model_class.from_pretrained(pretrained_model_name_or_path, *model_args, config=config, **kwargs)
  File "<redacted>/transformers/modeling_utils.py", line 463, in from_pretrained
    model = cls(config, *model_args, **model_kwargs)
TypeError: __init__() got an unexpected keyword argument 'output_hidden_states'
```

This works when loading directly from `transformers.FlaubertModel`.
Hi! the `output_hidden_states` should be specified in the configuration when loading from `AutoModel` classes. Doing the following is necessary to instantiate a class with hidden states:

```py
import transformers

config = transformers.AutoConfig.from_pretrained("flaubert-base-cased", output_hidden_states=True)
model = transformers.AutoModel.from_pretrained("flaubert-base-cased", config=config)
```

However, your issue showed me there was a bug with the loading of FlauBERT models with AutoModels, which I patched in https://github.com/huggingface/transformers/commit/ff6f1492e8296f511682fd56fcf62be0854723a2.
Please install from source to have the fix: `pip install git+https://github.com/huggingface/transformers`, I'll push a pypi patch for this soon.<|||||>Oh, okay, thanks. From what I understood of [AutoModel](https://huggingface.co/transformers/model_doc/auto.html#transformers.AutoModel.from_pretrained) doc, I thought all `**kwargs` in `AutoModel.from_pretrained` were passed to the config.<|||||>Indeed, the documentation seems misleading in that regard. I'm updating it.<|||||>`AutoTokenizer` seems to have the same problem as the one you fixed in `AutoModel`

```python
transformers.AutoTokenizer.from_pretrained("flaubert-base-uncased")
```

results in

```console
OSError: Model name 'flaubert-base-uncased' was not found in tokenizers model name list (xlm-mlm-en-2048, xlm-mlm-ende-1024, xlm-mlm-enfr-1024, xlm-mlm-enro-1024, xlm-mlm-tlm-xnli15-1024, xlm-mlm-xnli15-1024, xlm-clm-enfr-1024, xlm-clm-ende-1024, xlm-mlm-17-1280, xlm-mlm-100-1280)
```<|||||>Indeed it does, thanks @Evpok !<|||||>Should have been patched and tested with 1e82cd8.<|||||>Thanks for the quick response ♥<|||||>This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.
<|||||>I think this change should be bolder in documentations somehow as I had this problem too.