Remove vserver support
Some years ago, vservers were one of the main container technologies available on Linux. Unfortunately, it was never mainlined, and with better and more secure solutions like LXC, Docker, Xen and kvm now available, it seems that vserver usage has today become insignificant. The original authors of backupninja have migrated away from vservers some time ago, and it's currently unknown if there are any vserver users who use backupninja.
I therefore propose that vserver support be completely removed from backupninja.