Resolve "Save backups on project share"

Issue #21 (closed)

This script adds the functionality to transfer the backup data to our backup project share.

The gitlab-ci can't currently write directly to the project share but the smsbckp user can. So we run the transfer into a docker-container which runs with the uid and gid of the smsbckp user.

This will also change the backup functionality in that we only stay with the backups of the last 30 days on the prod vm, but save the backups of the last 180 days as well on the project share. It currently has 20 GB, so the demand on space should be ok for the moment.

I also tried to fix a problem with the minio backup (that the CI tries to poll the image to do it, but fails with it).

I'm still a litle bit unsure about the multiline syntax.