Setting dynamic values don't persist on save

[jtnelson]

Calling set(key, value) on a dynamic key that is not defined in the model doesn't actually get persisted to the database on save()

[jtnelson]

Unclear if this should be allowed. If we save dynamicData then we'd have to load it and rehydrate it when the Record is loaded. That would mean we need to load all the record data and assume any keys that are non-fields are dynamic. But going this route conflicts with the pre-select optimization where we load data from records by specifying keys. I guess we could also lazy load dynamic data and just do a db check at call time if dynamicData is being requested