Sample Corrupt Zipfile and Tests which currently fail #242

We have tests! These cause the failures I was seeing when I somehow got a bunch of dodgy zips the other day.

Repo.cs could do with a test case as well. We'll need a corrupt zip for it to download as it uses a URI rather than a file.
OMG, it's 0430 and I think I just woke my housemates laughing. Thank you. :)