VCF file zoo

[hammer]

We should collect weird VCFs and ensure we parse them correctly.

It would be nice if this zoo had metadata about what's interesting about a file.

@jeromekelleher can you point to your GA4GH zoo with VEP VCFs?

[jeromekelleher]

There's a handful of VCF files in here: https://github.com/ga4gh/ga4gh-server/tree/master/tests/data/datasets/dataset1/variants

[tomwhite]

Some previous work here: #432