Before this change the v2 signer sorted the headers for signing as
joined key:value pairs. However this put these two headers in the
wrong order.
x-amz-copy-source-range:
x-amz-copy-source:
This changes sorts on the keys before joining the values producing the
correct sort order.
x-amz-copy-source:
x-amz-copy-source-range:
This commit also adds some missing query parameters for signing that I
spotted in the s3cmd source.
2f0ef2e983