GitLab

* Add XLMRobertaForQuestionAnswering

* Formatting

* Make test happy

* Clean documentation

* add dialoGPT

* update README.md

* fix conflict

* update readme

* add code links to docs

* Update README.md

* Update dialo_gpt2.rst

* Update pretrained_models.rst

* Update docs/source/model_doc/dialo_gpt2.rst
Co-Authored-By: Julien Chaumond <chaumond@gmail.com>

* change filename of dialogpt
Co-authored-by: Julien Chaumond <chaumond@gmail.com>

* All Tokenizers

BertTokenizer + few fixes
RobertaTokenizer
OpenAIGPTTokenizer + Fixes
GPT2Tokenizer + fixes
TransfoXLTokenizer
Correct rst for TransformerXL
XLMTokenizer + fixes
XLNet Tokenizer + Style
DistilBERT + Fix XLNet RST
CTRLTokenizer
CamemBERT Tokenizer
FlaubertTokenizer
XLMRobertaTokenizer
cleanup

* cleanup