Hyperpartisan news detection
Thank you so much for working on this! This is awesome!

How much would it help you if we would remove the manual request?

We are naturally interested in getting some broad idea of how many people and who are using our dataset. But if you consider hosting the dataset yourself, I would rather remove this small barrier on our side (so that we then still get the download count from your library). This is an interesting aspect indeed!
Do you want to send me an email (see my homepage) and I'll invite you on our slack channel to talk about that?
@ghomasHudson wanna reach out to me as well? I tried to find your email to invite you without success.
Adding the hyperpartisan news detection dataset from PAN. This contains news article text, labelled with whether they're hyper-partisan and why kinds of biases they display.

Implementation notes:
- As with many PAN tasks, the data is hosted on [Zenodo](https://zenodo.org/record/1489920) and must be requested before use. I've used the manual download stuff for this, although the dataset is provided under a Creative Commons Attribution 4.0 International License, so we could host a version if we wanted to?
- The 'bias' attribute doesn't exist for the 'byarticle' configuration. I've added an empty string to the class labels to deal with this. Is there a more standard value for empty data?
- Should we always subclass `nlp.BuilderConfig`?

