VirtualBox-specific configuration file

This file contains settings that are specific to VirtualBox: the type of
NIC to use for networking, the location of the VBoxManage binary, and
the name of the VirtualBox VM group to use for the VMs.

Partial-Bug: 1312764
Implements: blueprint openstack-training-labs
Change-Id: I19bbf6c5314dc75704d7e2c15bb7607d6d11f279
Merge "VirtualBox-specific configuration file"