Check if redirects are being written to WARC file

[turicas]

If scrapy is skipping redirects, we may not be saving them.

[JustAnotherArchivist]

Based on a brief scan of Scrapy's and crau's codes, it appears that indeed, redirects are not preserved, though I have not tested this. Specifically, as far as I can tell, crau will write a request record for the initial request and a response record for the final response, and all intermediate responses and requests get ignored.

[turicas]

Fixed on e5c1ecb.