find a way to have us host s3 submission buckets for which all posted files are readable

[RZachLamberty]

docs to start with

last year what worked was having users create s3 buckets and granting us permissions

what didn't work was us creating an s3 bucket and granting users permissions. the main problem was that we thought this approach would be effortless for users, but they had to set the ACL on every file they uploaded -- not good.