Torch.hub now based on AutoModels - Updating AutoModels with AutoModelWithLMHead, Sequence Classification and Question Answering
Author: LysandreJik
Pull request: yes

Added new AutoModels, as long as the accompanying tests. Updated the TorchHub configuration file to redirect to those AutoModels.

Comments:
# [Codecov](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110?src=pr&el=h1) Report
> Merging [#1110](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/pytorch-transformers/commit/df9d6effae43e92761eb92540bc45fac846789ee?src=pr&el=desc) will **decrease** coverage by `0.04%`.
> The diff coverage is `73.33%`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110/graphs/tree.svg?width=650&token=9qOlN6Hb1c&height=150&src=pr)](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #1110      +/-   ##
==========================================
- Coverage   79.61%   79.56%   -0.05%     
==========================================
  Files          42       42              
  Lines        6898     6965      +67     
==========================================
+ Hits         5492     5542      +50     
- Misses       1406     1423      +17
```


| [Impacted Files](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pytorch\_transformers/tests/modeling\_auto\_test.py](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110/diff?src=pr&el=tree#diff-cHl0b3JjaF90cmFuc2Zvcm1lcnMvdGVzdHMvbW9kZWxpbmdfYXV0b190ZXN0LnB5) | `98.18% <100%> (+2.18%)` | :arrow_up: |
| [pytorch\_transformers/modeling\_auto.py](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110/diff?src=pr&el=tree#diff-cHl0b3JjaF90cmFuc2Zvcm1lcnMvbW9kZWxpbmdfYXV0by5weQ==) | `51.72% <54.54%> (-4.28%)` | :arrow_down: |
| [pytorch\_transformers/modeling\_utils.py](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110/diff?src=pr&el=tree#diff-cHl0b3JjaF90cmFuc2Zvcm1lcnMvbW9kZWxpbmdfdXRpbHMucHk=) | `84.18% <0%> (+0.76%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110?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/pytorch-transformers/pull/1110?src=pr&el=footer). Last update [df9d6ef...84a3a96](https://codecov.io/gh/huggingface/pytorch-transformers/pull/1110?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).


Not sure torch.hub will work directly. We should check with @VictorSanh.

Just checked the integration with Pytorch Hub, it works on my end. For example, you can try it out with: 

```python
import torch
torch.hub.load('huggingface/pytorch-transformers:automodels', 'autoModelWithLMHead', 'distilbert-base-uncased')
```

Ok, I think we are all good with this. Happy to have `torch.hub` integration again.