The ApplyUpdates() method on the reputation.DB interface acts like the
similar Update() method, but can allow for applying the changes from
multiple audit events, instead of only one.
This will be necessary for the reputation write cache, which will batch
up changes to each node's reputation in order to flush them
periodically.
Refs: https://github.com/storj/storj/issues/4601
Change-Id: I44cc47767ea2d9423166bb8fed080c8a11182041
