[AR >= 5.1] Do not change updated_at on create_or_update if nothing was changed

[Stefan Exner]

Currently, a record's updated_at column is altered on create_or_update calls (save, update_attributes, ...) even if neither attributes nor settings were changed.

In vanilla AR >= 5.1, this is not the case and setting_accessors should therefore behave the same way and not change the updated_at column.