Add alog to application

I am thinking of adding [alog](https://github.com/dwyl/alog) to this project.

When this project was created alog did not exist. This project has similar features to alog in that it does not update any of the comments on an issue, instead it adds a new `version` of the comment to the `versions` table in the database.

However if an issue name is ever updated then github-backup just updates the record in the database.

With alog we can easily make each table of this application (that needs to be append-only) append-only.