don't encrypt the local-tar metadata file, so it can be accessed with…

[jason-adnuntius]

…out the private key when doing delta backups

This makes it possible to only use the public key for backups, and only need the private key for restores. This issue only occurs when trying to remove old backups, without the private key being in the config file, its impossible to open the metadata file and thus remove the old data files.

Why this way

The metadata file does not have any sensitive information, so encrypting it seemed a bit pointless and I made the simplest change that could possibly work.