Intelligently configure VirtualBox networking

This change provides a mechanism to create only the necessary host-only network interfaces needed for getting BCPC up and running with VirtualBox.

The existing behavior removed all host-only interfaces and recreate `vboxnet[0-2]` to be used by BCPC.  This behavior is problematic when using other VirtualBox VMs and appliances that also need their own host-only interface setup.

The pull request provided introduces an alternative mechanism for determining if an existing interface is suitable to be used; if one is found, the name is stored for later use.  Otherwise, a new network interface and configuration is provided for each network that was unable to use an existing interface.