Add certificates folder to backup and restore

[bautisflow]

Give the case that an additional certificate has been placed into the folder, this would allow this certificate to be restored.

[bautisflow]

As this issue requires additional code to in order to append to an existing archive additional files, it encourages the enhancement of the tar utility to make it better, easier to use and tested.

We should account that already compressed, created and closed archives cannot be extended easily. So we could keep the archives open and write new entries instead of closing, reopening and appending.