add model_card flaubert-base-uncased-squad
A baseline model for question-answering in french ([flaubert](https://github.com/getalp/Flaubert) model fine-tuned on [french-translated SQuAD 1.1 dataset](https://github.com/Alikabbadj/French-SQuAD))

Small error when trying it with the pipeline though:

```python-traceback
>>> nlp = pipeline('question-answering', model='fmikaelian/flaubert-base-uncased-squad', tokenizer='fmikaelian/flaubert-base-uncased-squad')

nlp({
    'question': "Qui est Claude Monet?",
    'context': "Claude Monet, né le 14 novembre 1840 à Paris et mort le 5 décembre 1926 à Giverny, est un peintre français et l’un des fondateurs de l'impressionnisme."
})

Model name 'fmikaelian/flaubert-base-uncased-squad' was not found in model name list (bert-base-uncased, bert-large-uncased, bert-base-cased, bert-large-cased, bert-base-multilingual-uncased, bert-base-multilingual-cased, bert-base-chinese, bert-base-german-cased, bert-large-uncased-whole-word-masking, bert-large-cased-whole-word-masking, bert-large-uncased-whole-word-masking-finetuned-squad, bert-large-cased-whole-word-masking-finetuned-squad, bert-base-cased-finetuned-mrpc, bert-base-german-dbmdz-cased, bert-base-german-dbmdz-uncased, bert-base-japanese, bert-base-japanese-whole-word-masking, bert-base-japanese-char, bert-base-japanese-char-whole-word-masking, bert-base-finnish-cased-v1, bert-base-finnish-uncased-v1, bert-base-dutch-cased, openai-gpt, transfo-xl-wt103, gpt2, gpt2-medium, gpt2-large, gpt2-xl, distilgpt2, ctrl, xlnet-base-cased, xlnet-large-cased, 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, roberta-base, roberta-large, roberta-large-mnli, distilroberta-base, roberta-base-openai-detector, roberta-large-openai-detector, distilbert-base-uncased, distilbert-base-uncased-distilled-squad, distilbert-base-cased, distilbert-base-cased-distilled-squad, distilbert-base-german-cased, distilbert-base-multilingual-cased, distilbert-base-uncased-finetuned-sst-2-english, albert-base-v1, albert-large-v1, albert-xlarge-v1, albert-xxlarge-v1, albert-base-v2, albert-large-v2, albert-xlarge-v2, albert-xxlarge-v2, camembert-base, umberto-commoncrawl-cased-v1, umberto-wikipedia-uncased-v1, t5-small, t5-base, t5-large, t5-3b, t5-11b, xlm-roberta-base, xlm-roberta-large, xlm-roberta-large-finetuned-conll02-dutch, xlm-roberta-large-finetuned-conll02-spanish, xlm-roberta-large-finetuned-conll03-english, xlm-roberta-large-finetuned-conll03-german, flaubert-small-cased, flaubert-base-uncased, flaubert-base-cased, flaubert-large-cased). We assumed 'https://s3.amazonaws.com/models.huggingface.co/bert/fmikaelian/flaubert-base-uncased-squad/modelcard.json' was a path or url to a model card file named modelcard.json or a directory containing such a file but couldn't find any such file at this path or url.
Creating an empty model card.
>>> 
>>> nlp({
...     'question': "Qui est Claude Monet?",
...     'context': "Claude Monet, né le 14 novembre 1840 à Paris et mort le 5 décembre 1926 à Giverny, est un peintre français et l’un des fondateurs de l'impressionnisme."
... })
convert squad examples to features: 100%|██████████████████████████████████████████████████████████████████████████████████████████| 1/1 [00:00<00:00,  3.25it/s]
add example index and unique id: 100%|███████████████████████████████████████████████████████████████████████████████████████████| 1/1 [00:00<00:00, 4181.76it/s]
Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
  File "/usr/local/lib/python3.7/site-packages/transformers/pipelines.py", line 815, in __call__
    start, end = self.model(**fw_args)
ValueError: too many values to unpack (expected 2)
```
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/2833?src=pr&el=h1) Report
> Merging [#2833](https://codecov.io/gh/huggingface/transformers/pull/2833?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/f54a5bd37f99e3933a396836cb0be0b5a497c077?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/2833/graphs/tree.svg?width=650&token=9qOlN6Hb1c&height=150&src=pr)](https://codecov.io/gh/huggingface/transformers/pull/2833?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master    #2833   +/-   ##
=======================================
  Coverage   75.02%   75.02%           
=======================================
  Files          93       93           
  Lines       15275    15275           
=======================================
  Hits        11460    11460           
  Misses       3815     3815
```



------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/2833?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/2833?src=pr&el=footer). Last update [f54a5bd...286b4fa](https://codecov.io/gh/huggingface/transformers/pull/2833?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
