novastats: Update some reports to use more up-to-date code.

Authored by Andrew on May 12 2017, 10:45 PM.

Description

novastats: Update some reports to use more up-to-date code.

The old 'novastats.py' library is no longer needed since mwopenstackclients
does most of the querying we want. This patch replaces some old scripts
with a few newer example scripts that use mwopenstackclients.

Change-Id: I8e054c973dcdaa731688788b5087043308779f96