Fix PL token classification examples
Author: vblagoje
Pull request: yes

This PR fixes the following:

- fetches germeval_14 dataset from a new [location](https://drive.google.com/drive/folders/1kC0I2UGl2ltrluI9NqDjaQJGw5iliw_J)  where it has been moved recently (cc @stefan-it)
- correctly implements `def get_dataloader(self, mode: int, batch_size: int, shuffle: bool = False) -> DataLoader:` from BaseTransformer PL parent class (cc @sshleifer )

I have verified both normal and PL training works as expected. Will add tests as we rework examples to use datasets

Comments:
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/6682?src=pr&el=h1) Report
> Merging [#6682](https://codecov.io/gh/huggingface/transformers/pull/6682?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/d0e42a7bed3de9271ae39c575d7eeb54cf985921?el=desc) will **increase** coverage by `0.51%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/6682/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/6682?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #6682      +/-   ##
==========================================
+ Coverage   79.14%   79.66%   +0.51%     
==========================================
  Files         156      156              
  Lines       28248    28248              
==========================================
+ Hits        22358    22503     +145     
+ Misses       5890     5745     -145     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/6682?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/modeling\_tf\_xlnet.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl94bG5ldC5weQ==) | `21.12% <0.00%> (-71.05%)` | :arrow_down: |
| [src/transformers/modeling\_tf\_flaubert.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9mbGF1YmVydC5weQ==) | `24.53% <0.00%> (-63.81%)` | :arrow_down: |
| [src/transformers/modeling\_roberta.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ19yb2JlcnRhLnB5) | `77.37% <0.00%> (-19.71%)` | :arrow_down: |
| [src/transformers/file\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9maWxlX3V0aWxzLnB5) | `82.41% <0.00%> (+0.25%)` | :arrow_up: |
| [src/transformers/modeling\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ191dGlscy5weQ==) | `88.05% <0.00%> (+0.55%)` | :arrow_up: |
| [src/transformers/modeling\_tf\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl91dGlscy5weQ==) | `86.64% <0.00%> (+1.95%)` | :arrow_up: |
| [src/transformers/generation\_tf\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9nZW5lcmF0aW9uX3RmX3V0aWxzLnB5) | `86.46% <0.00%> (+3.75%)` | :arrow_up: |
| [src/transformers/configuration\_t5.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9jb25maWd1cmF0aW9uX3Q1LnB5) | `96.42% <0.00%> (+10.71%)` | :arrow_up: |
| [src/transformers/modeling\_t5.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190NS5weQ==) | `83.83% <0.00%> (+12.21%)` | :arrow_up: |
| [src/transformers/modeling\_tf\_t5.py](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl90NS5weQ==) | `90.93% <0.00%> (+64.09%)` | :arrow_up: |
| ... and [1 more](https://codecov.io/gh/huggingface/transformers/pull/6682/diff?src=pr&el=tree-more) | |

------

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> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/6682?src=pr&el=footer). Last update [d0e42a7...2f843e6](https://codecov.io/gh/huggingface/transformers/pull/6682?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).


@stefan-it At the bottom of the germeval [page](https://sites.google.com/site/germeval2014ner/data?authuser=0) I found the new location for the datasets (see Downloads section)

would love tests!

I will start working on them @sshleifer

I updated the urls a while ago in this PR https://github.com/huggingface/transformers/pull/6571 😅

> I updated the urls a while ago in this PR #6571 😅

Apologies @stefan-it, I didn't know about it. There was an error in PL version of the training so I thought why not fix the dataset URL as well. I am following you now so I'll know more about your PRs. Will you fix the NLP dataset germeval_14 as well?

@vblagoje Thanks for this!!

please reach out to me on [Lightning's Slack](https://join.slack.com/t/pytorch-lightning/shared_invite/zt-f6bl2l0l-JYMK3tbAgAmGRrlNr00f1A) (username same as here on github) or email me: `nate [at] pytorchlightning.ai`. I'm about to make updates across examples this week and would love to sync up with you on this.