Create a repository for datasets/revive the Dataset module

[ihodes]

We don't want to have to download FASTAs from random FTP servers as part of our workflow; it'd be nice to have a verified repository of FASTAs/VCFs/etc that workflows can use.

[arahuja]

Curious as what advantage this brings? I think ensembl's FTP server is a "verified repository of FASTAs/VCFs/etc"

[ihodes]

I'd prefer if our workflows were not dependent on someone else's FTP server being up, if they don't have to. We also don't just rely on ensembl; some other providers may be less concerned with uptime.