Previously it was necessary to work around large files failing to
download with `--acd-templink-threshold`. This change makes that flag
obsolete and all files should download. Templinks may be useful under
some circumstances though the flag isn't being removed.
It does this by filtering `Authorization:` headers out in the
transport if the authorization is supplied in the URL. This prevents
the "Only one auth mechanism allowed; only the X-Amz-Algorithm query
parameter, Signature query string parameter or the Authorization
header should be specified" error from AWS.
Nick Craig-Wood
6448c445f5