Vault update fix (partly induces by faulty merge)

The last pull requests had some conflicts. I hope this PR solves these.

Additionally I changed the logic of the backup question a little bit and added German translations. 

@Doplgangr I don't know if the backup in the background is the best way for the backup prior to the vault update, because the update cant be automatically executed after the backup, which would be nice. 

I still think that the restore job should delete the vault folder before, because otherwise you might end up with a mixed state vault. E.g. If one upgrades an old ECB vault, starts the update and tries to restore his backup afterwards, he end in an undefined state where new and old files are present in the vault.