The current code configures port forwarding to the VM from all host
interfaces.
Most users probably don't want to expose their unsecured VMs to their
local network (or worse).
This patch limits port forwarding to the host's 127.0.0.1 interface.
Partial-Bug: 1312764
Implements: blueprint openstack-training-labs
Change-Id: Ib28439c728691510ac710544564e92193e66bf52
238dcbc2b9