Remove riak_cs_s3_response dependency from mp_upload_test

`mp_upload_test' uses riak_cs_s3_response to in one of its assertion.
But it shouldn't in integration tests. Not sure why it has been
passing tests before.
Add comma
Merge pull request #966 from basho/bugfix/copy-cs-module-fix

Remove riak_cs_s3_response dependency from mp_upload_test

Reviewed-by: shino