==> default: Mounting shared folders... default: /vagrant => /Users/****/projects/foo/middleman/VM Failed to mount folders in Linux guest. This is usually because the "vboxsf" file system is not available. Please verify that the guest additions are properly installed in the guest and can work properly. The command attempted was: mount -t vboxsf -o uid=`id -u vagrant`,gid=`getent group vagrant | cu