🚀 Add missing tokenizer test files

Several tokenizers currently have no associated tests. I think that adding the test file for one of these tokenizers could be a very good way to make a first contribution to transformers.

Tokenizers concerned

not yet claimed

• LED

• RemBert

• ConvBert

• RetriBert

claimed

• Flaubert @anmolsjoshi
• Longformer

🐛 Bug

File "/home/ubuntu/vqa/GMN/mmf/mmf/datasets/builders/visual_genome/dataset.py", line 44, in init
scene_graph_file = self._get_absolute_path(scene_graph_file)
AttributeError: 'VisualGenomeDataset' object has no attribute '_get_absolute_path'

Command that i run in shell

CUDA_VISIBLE_DEVICES="0" mmf_run config=projects/gmn/configs/visual_genome/defaults.yaml model=gm

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  paddle版本2.0.8 paddlenlp版本2.1.0
  建议，能否在paddlenlp文档中，整理列出各个模型的tokenizer是基于什么类别的based，如bert tokenizer是word piece的，xlnet tokenizer是sentence piece的，以及对应的输入输出样例

Hi
when I do classification with the pretrained vggface2 model, how do I match a probability to a name? do you have a list of labels for the trained model?

Thanks

The Mock object shouldn't be there..

RTD

Latest
![image](https://user-images.githubusercontent.com/18496796/114235740-e910fb80-9980-11eb

I've been chatting with some others interested in training CLIP for different domain tasks. They expressed interest in a simple way to use a pre-trained text transformer.

Some basic support for Hugging Face or generic classes of transformers shouldn't be too crazy of an extension to what is already fleshed out.