Some aws implementations, for example the quobyte object storage, do not
support the v4 signing algorithm, but only v1.
This makes it possible to configure the signatureVersion.

The algorithm implementation was ported from https://github.com/oNestLab/botocore/blob/d6c1be296e8cfe0706cb0c8bbcad9c095d0f4d09/botocore/auth.py#L860-L862
which is used by the aws CLI client.

This fixes https://github.com/heptio/ark/issues/811

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Signed-off-by: Bastian Hofmann <bashofmann@gmail.com>