Fix object copy requests.

Currently, we run PUT Object Copy  without 'content-length: 0' or 'transfer-encoding: chunked' returns '411 Length Required'.
This is because Swift returns 'HTTPLengthRequired' when we run object copy without them.
AWS is not required them, so I add ’Content-Length: 0' to Switf3's internal processing.

Change-Id: Ie0b02f49662301de3aa3d3b93d730d2cdf98b66e
Merge "Fix object copy requests."