Vagrant kfreebsd base box?

[Luca Favatella <luca.favatella@gmail.com>]

Hi,

FYI I drafted a kfreebsd-amd64 Vagrant base box. I hope to polish it
and propose pull request but not sure when so feel free to take the
lead on this if you want.

(The idea is that kfreebsd-* Vagrant boxes would help contributions to
the kfrebsd-* ports by developers hacking on GNU/kFreeBSD only
intermittently.)

Code is available at
https://github.com/lucafavatella/debian-vm-templates/commit/1923592d19686a3ccf2293b5a70ee716913de10e

It builds box but a late step fails trying to mount some kind of
shared folder specific to VirtualBox - maybe the option
`"guest_additions_mode": "disable"` does not work in packer?
```
$ packer --version
0.8.6
```

Sample error log output below.

Cheers
Luca


```
$ make oldstable-kfreebsd-amd64-test
...
==> default: Mounting shared folders...
    default: /vagrant =>
/Users/luca/dev/debian/debian-vm-templates/packer-virtualbox-vagrant
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 | cut
-d: -f3` vagrant /vagrant
mount -t vboxsf -o uid=`id -u vagrant`,gid=`id -g vagrant` vagrant /vagrant

The error output from the last command was:

stdin: is not a tty
mount: vagrant : No such device

make: *** [oldstable-kfreebsd-amd64-test] Error 1
```