Copy API doesn't copy user meta data. [JIRA: RCS-153]

[ksauzz]

S3 object can contain user meta data which are stored by 'x-amz-meta-*' header on PUT Object, and 'PUT Object - Copy' API should copy these meta data. Riak CS doesn't do that.

This bug is found by one of ceph tests. After the fix, the test can be enabled.

reproduction

put a object with 2 meta data.

% s3curl.pl --id user --put Makefile -- -x localhost:8080  http://test.s3.amazonaws.com/1 -H "x-amz-meta-param1: value1" -H "x-amz-meta-param2: value2" -i
HTTP/1.1 100 Continue

HTTP/1.1 200 OK
Server: Riak CS
ETag: "487d4776ae93cc20feddd887e1226fc8"
Date: Thu, 19 Mar 2015 07:32:04 GMT
Content-Type: text/plain
Content-Length: 0

get a object

% s3curl.pl --id user -- -x localhost:8080  http://test.s3.amazonaws.com/1 -X HEAD -i
HTTP/1.1 200 OK
x-amz-meta-param2: value2               <---- meta data
x-amz-meta-param1: value1               <---- meta data
Server: Riak CS
Last-Modified: Thu, 19 Mar 2015 07:32:04 GMT
ETag: "487d4776ae93cc20feddd887e1226fc8"
Date: Thu, 19 Mar 2015 07:32:18 GMT
Content-Type: application/octet-stream
Content-Length: 6239

copy a object

% s3curl.pl --id user --copySrc test/1 -- -x localhost:8080  http://test.s3.amazonaws.com/2 -H "Content-Length: 0" -i
HTTP/1.1 200 OK
Server: Riak CS
ETag: "487d4776ae93cc20feddd887e1226fc8"
Date: Thu, 19 Mar 2015 07:33:46 GMT
Content-Type: application/xml
Content-Length: 175

<?xml version="1.0" encoding="UTF-8"?><CopyObjectResult><LastModified>2015-03-19T07:33:46.000Z</LastModified><ETag>"487d4776ae93cc20feddd887e1226fc8"</ETag></CopyObjectResult>

get a copied object

% s3curl.pl --id user -- -x localhost:8080  http://test.s3.amazonaws.com/2 -X HEAD -i
HTTP/1.1 200 OK
Server: Riak CS
Last-Modified: Thu, 19 Mar 2015 07:33:46 GMT                    <------ no meta data
ETag: "487d4776ae93cc20feddd887e1226fc8"
Date: Thu, 19 Mar 2015 07:34:21 GMT
Content-Type: application/octet-stream
Content-Length: 6239

[shino]

Quote from AWS doc [1]

When copying an object, you can preserve most of the metadata (default) or specify new metadata.
However, the ACL is not preserved and is set to private for the user making the request.

[1] PUT Object - Copy - Amazon Simple Storage Service
http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectCOPY.html

[shino]

Will be addressed by #1212

[Basho-JIRA]

For release note: this change is part of RCS-257, please refer its comment.

_[posted via JIRA by Shunichi Shinohara]_