collectfast Fix/AWS Multipart Hashes

Here's a first draft of changes to handle hashing multipart uploads to match the ETag on S3. I'm really not sure about the structure of the change, let me know if you'd like it implemented some other way.

I wasn't able to get the live test running locally but I think it should pass. I tested with a project of mine and it seems to work.

Gzip support is not implemented at this point.

Fixes #201

Jul 01 '20 15:07 sean-wallace

Thanks for putting in the work on this! I ran the test suite locally on your branch the the suite is passing.

It would be really nice to maintain support for gzip, that should be especially relevant for projects with large files. Is it feasible to make that happen?

Jul 02 '20 14:07 antonagestam

Ok, I think this is ready for another look. Pretty significant changes were necessary to implement the gzip stuff because of the way the Class inheritance is set up.

Do you mind if I squash the branch?

Jul 04 '20 18:07 sean-wallace

Very nice work with moving this forward! I had a few more comments.

Thanks very much for the thoughtful and constructive review -- I've made the changes generally as suggested. Let me know what you think.

Jul 11 '20 15:07 sean-wallace