Signed-off-by: Stephen J Day <stephen.day@docker.com>
Vendored resumable sha256/sha512 library. Digest package new exports a resumable variant of the Digester. Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
Also includes goamz PR #331 for s3 v4 auth + IAM role support