labs: rudimentary verification of installed services

The current scripts make no effort to verify that the installed
services are configured correctly.

With this patch, some basic configuration errors will at least leave
traces in the script log files.

Change-Id: I4c85f81c1540ff50a8a690dc170871fc56667f7d
Co-Authored-By: Pranav Salunke <dguitarbite@gmail.com>
Implements: blueprint openstack-training-labs