Add automatic restore

[MartinPaulEve]

We should give the user the option to automatically restore a backup.

This would consist of specifying a JSON/SQL file + version, and a media/paths zip.

The media/paths zip needs to contain a new metadata file that maps directories in the zip into the original FS.

Before taking action, we should print precisely what action is going to be taken, as this will be destructive on the FS + database. The user should then have to confirm this.