Feed importer allows invalid images

[cavis]

Import a feed with an invalid top-level itunes image (< 1400x1400, for example)

What happens:

• Import succeeds, kicks off an async cms-image-lambda
• Image callback worker starts, updates CMS db, announces to feeder
• Feeder story/episode update worker starts, gets image, checks dimensions itself
• Feeder fails to update episode due to validation error, rejects change

I guess I'm not quite clear what to expect in this scenario, since there's an async image worker involved. But it would be nice if we showed this invalid image error to the user somewhere - either in the import tab or on the series basic-info. Just a warning that "hey, that image on your previous feed should be > 1400x1400".

[cavis]

Question: could we call Porter synchronously, just to check the image dimensions?

Or maybe we just wait until we're actively resizing (upsizing?) images to meet the feed requirements.