Load data for missing readme

[jonthegeek]

{ttmeta} ran into an issue for tt_load(2018,8) (https://tidytues.day/2018/2018-05-21). That week doesn't have a README, so we need to skip that step. This used to work, so I want to make it work, but the easier fix is probably to add a README to any missing weeks (so I might still end up doing that). We really shouldn't care about the week's readme, though, or at least we should fail gracefully.

[jonthegeek]

The readme isn't the problem, it's that it's a zip file, and I for some reason completely disabled that. Tracking down old code to figure out how it used to work, and making sure it still works at least that well!