Sync 331

Thanks @mseaton!
My contention is that payload is not a field of the SyncRecord object.  It is a column in the database and in the sync transmission because it is a serialized representation of the LinkedHashMap<String, SyncItem> property.  It is this Map of SyncItems that is the true property of SyncRecord and not the payload.  So I think it does not belong here, and it's not worth messing with it if there is no value.  You gain nothing by putting those methods directly on SyncRecord that you would otherwise gain by putting that functionality in a utility method as I suggest.