Automatically attach attribution information to bucket during
BeginObject or CreateBucket when the UserAgent is set.
Change-Id: I405cb26c5a2f7394b30e3f2cf5d2214c8781eb8b
uuid.UUID implements driver.Value so it can be directly used as a
scannable result.
Replace uses of dbutil.BytesToUUID with uuid.FromBytes.
Change-Id: I51a670185ceb3cc2199d5aa2b76bc3fc191ca8fe