Add experimental backup plan

[davidsandilands]

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[davidsandilands]

Current issues and followup tickets

• Restoring CA on a server of a different name from backup fails. This is the intended behaviour of the pe-backup script but not really our intended behaviour.
• Rspec has failures which have been marked as pending. I suspect this will be too complicated due to functions but a follow up ticket should review
• Puppetdb does not have a reinitalise replica command. Testing looked succesful without reinitialising but following up in more detail would be wise
• the database backup was changed to a directory format from file to match in with pe-backup scripts this should be reviewed
• the replica does not get the secret key automatically
• the documents https://docs.google.com/document/d/13ApJxE3Bj-ro1eWvCTiDkP0zq4iqWzidK2NtlK0T8YA/edit#heading=h.yw75i0d7moov and https://docs.google.com/document/d/1qv0Czw8l6I6yIUKehGX5dz19GWZ8QjLfE5sRrQOAsR4/edit?pli=1#heading=h.bbnocibnbenl should be updated following work
• the backup goes to a directory with a timestamp, creating a zipped archive would be simpler