Now using ini_file to parse nova.conf

nova.conf now contains sections, one of which keystone_authtoken
contains the keystone credentials. This commit makes use of
a nova_config that was rewritten to use ini_file. Packstack no
longer touches api-paste.ini

The commit to update the nova puppet module was cherry picked from
https://github.com/Mirantis/puppetlabs-nova
and written by
Vladimir Kuklin <vkuklin@mirantis.com>
https://github.com/aglarendil

This is the nova part of
https://bugzilla.redhat.com/show_bug.cgi?id=888725
cinder next

Change-Id: I9795e3803fc5511128a279f99a4a750f08867b8a