Force the use of Virtualbox
Force the use of Virtualbox

Some plugins will change the default provider from Virtualbox to
LXC (for example). This will not only force the use of Virtualbox,
but it will guarantee that other providers aren't accidentally
used because the box only works under VB.

nanasess/vagrant-freebsd,wunki/vagrant-freebsd,oddnoc/vagrant-freebsd