cls_rgw: implement dump() and generate test instances

Add missing methods for some cls_rgw op types.

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
cls_rgw: clean up compilation warnings

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: remove unused code

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>