Add Hate Speech and Offensive Language Detection dataset
@lhoestq done! The failing testes don't seem to be related, it seems to be a connection issue, if I understand it correctly. @lhoestq done! merging since the CI is fixed on master
Add [Hate Speech and Offensive Language Detection dataset](https://github.com/t-davidson/hate-speech-and-offensive-language) from [this paper](https://arxiv.org/abs/1703.04009).