Strip leading / from x-amz-copy-source header
Strip leading / from x-amz-copy-source header

Previously S3Proxy did not update copySourceHeader.  Fixes #10.

kahing/s3proxy,andrewgaul/s3proxy,flandr/s3proxy,kahing/s3proxy,timuralp/s3proxy,bouncestorage/s3proxy,bouncestorage/s3proxy,flandr/s3proxy,andrewgaul/s3proxy,timuralp/s3proxy