http://unix.stackexchange.com/questions/129305/how-can-i-enable-access-to-usb-devices-within-virtualbox-guests
$ sudo usermod -a -G vboxusers <username>
$ cat /etc/group |grep vbox
vboxusers:x:129:lkh
without group
$ VBoxManage list usbhost
Host USB Devices:
<none>
with group
