Add Changelog

[esscott]

As a data entry person, after I make corrections to my data according to the error report and re-upload the CSV, I want this revised version to replace the old version, so that the data remains organized and duplicate free.

• [ ] User is required to click to confirm replacement action
• [ ] Implement version control methods to "soft" delete (mark as deleted but retain data until a certain point)

[justinpac]

Data should not be immutable. A Change log has already been implemented but we need to demo it to ensure it is what Stuart et al want.