Add network configuration templates

This changeset adds templates used by osbash/wbatch guest-side scripts
when creating network configuration files.

The template-ubuntu-interfaces-* files are for /etc/network/interfaces
(as used by Ubuntu and Debian).

The template-fedora-ifcfg-* files are for ifcfg-<interfacename> files
in /etc/sysconfig/network-scripts/ (as used by Fedora).

Partial-Bug: 1312764
Implements: blueprint openstack-training-labs
Change-Id: I0aebc71e416bf931aa698d66d9e135ba05fda017
Merge "Add network configuration templates"