CBQE-0: bucket var should be object attribute

Change-Id: I64c29fc892dcb034c20f2596109c241106f7909d
Reviewed-on: http://review.couchbase.org/26051
Reviewed-by: Tommie McAfee <tommie@couchbase.com>
Tested-by: Tommie McAfee <tommie@couchbase.com>