change making dropbox author and email to be part of payload, not persisted

I move the author/email dropbox info to be part of the payload (not persisted settings).

(1) Semantically correctness.  The dropbox payload contains the delta and author.
(2) Improve initial linking to dropbox perf.  No need to call Kudu to set dropbox author settings).
(3) Avoid unnecessarily polluting of persisted settings.