FreeBSD-10: Reduce box size

Creates a box that is only 700MB - using the method from @wunki's [setup script](https://github.com/wunki/vagrant-freebsd/blob/master/bin/vagrant-setup.sh#L87)

```
-rw-r--r--    1 scollins  staff   701M Jan 25 19:17 freebsd10.box
```