Draft: Split Request class for s3acl

This is a draft version for spliting Request class.

We should keep clean controller classes to clarify
what swift3 have to handle. However acl handling for s3_acl
looks to be leaked into controller side.

If moving such routine into Request class, absolutely
Request class will become a complex large class.
That is why I try to split Request class and create a new class
called S3ACLRequest class. Basically it is a wrapper of original
Request class so that we can add acl handlers into anywhere
new S3ACLRequest without breaking original Request class.

This is still in WIP. As a next step, trying to move whole acl
handling code into S3ACLRequest.

Change-Id: I5a8e9a32cb47c135fb97d51ef53bbd98cabff67f