S3 AWS Signature Version 4 for presigned temporary URLs

[cyberduck]

326b02d created the issue

New Amazon S3 regions like Frankfurt supports only AWS4 authentication scheme.
Using Signed temporary URLs for Frankfurt region gives an error: "The authorization mechanism you have provided is not supported. Please use AWS4-HMAC-SHA256."

[cyberduck]

@dkocher commented

In d15c75e.