Add GoEmotions
Whoops, didn't mean for that to be merged yet (my bad). I'm reaching out to the authors since we'd like their feedback on the best way to have the `author` field anonymized or removed. Will send a patch once they get back to me.
Adds the GoEmotions dataset, a nice emotion classification dataset with 27 (multi-)label annotations on reddit comments. Includes both a large raw version and a narrowed version with predefined train/test/val splits, which I've included as separate configs with the latter as a default.

- Webpage/repo: https://github.com/google-research/google-research/tree/master/goemotions
- Paper: https://arxiv.org/abs/2005.00547