Substitute riak-cs by netcat to vatch the sent request
$> nc -l 127.0.0.1 8080
PUT /53208b5294da268379000001?AWSAccessKeyId=O_5H9U1UTJNVB5MDNM0O&Expires=1394677746&Signature=IjMEUg%2BH%2FP7SP5nx4KW7gXJ6h8g%3D HTTP/1.1
Host: 52aed41a94da26d8fa000001.data.riak.dev
Content-Length: 2831
x-amz-acl: public-read
...