Set PLACK_ENV for cgis

[aelkiss]

Staged on dev-1. This should prevent the default Plack middleware from being loaded, which generated stack traces.

[carylwyatt]

I tried a bunch of weird query params and I never saw the error screen I've been getting on dev-3 and localhost.

If I leave out the seq parameter, I still get a download screen, for example https://dev-1.babel.hathitrust.org/cgi/imgsrv/image?id=pur1.32754063106516&attachment=1&tracker=D1&format=image%2Ftiff&size=ppi%3A300

Same when I leave out seq but add a nonsense param: https://dev-1.babel.hathitrust.org/cgi/imgsrv/image?id=pur1.32754063106516&attachment=1&tracker=D1&nothing=nope&format=image%2Ftiff&size=ppi%3A300

I'm assuming there's a default seq in the code somewhere?

That's the only thing I noticed though, and this looks good to me!

[aelkiss]

Yes, I think that's what we saw earlier in sprint planning in looking at this. I think it defaults to the cover. I'm not sure if anything relies on that behavior but I don't think it's harmful to keep. @moseshll Let me know if you have any concerns with this, otherwise I think we can get this deployed on Monday.

[moseshll]

This looks good to me, after comparing dev-1 to dev-2. I'll try to have the bogus seq patch ready to go in the near future.