Add osbash/Vagrant-specific configuration files

This changeset adds two configuration files, one for osbash and one for
Vagrant.

They contain the names of the VirtualBox shared folder and the
shell user. For osbash, there are some additional variables.

These config files could presumably be moved outside of the config
directory or disappear entirely, because there seems to be little
benefit in having these variables configurable.

Partial-Bug: 1312764
Implements: blueprint openstack-training-labs
Change-Id: Ieb0928debee463ef7211dae679ac38a6702ad084
Merge "Add osbash/Vagrant-specific configuration files"