we will switch over our tgz module to node-tar. Main advantage is that
it is used by npm. Currently, we have our own fork to ignore stat errors
in the other module.
unfortunately, I cannot get this to work with the create logic. It doesn't
support path modification - https://github.com/isaacs/node-tar/issues/271
so, will revert this immediately and keep this for future
notes:
* backup root cannot come from backend. for dynamic mounts backend cannot know where it is mounted
* backupConfig is 3 parts - format / mount / password . there is also this rootPath (which should not be in db)
* password should be stored separately in settings at some point
* format has to be passed along everywhere because we allow restore from same backupConfig but different format. we do this by saving the format in the backups table
fixes#819
