Add basic structure for ReNo

ReNo [1] is the release management tool in OpenStack.
This patch adds the basic structure to start using it.

* Update .gitignore
* Add a basic note "use-reno"
* Add releasenotes/ dir and basic files
* Add python files: setup.cfg, setup.py, test-requirements.txt and
  tox.ini.

[1] http://docs.openstack.org/developer/reno

Change-Id: Ia1e1159c9b86660c328680ef6519297d0921b5cc

setup.cfg

@@ -0,0 +1,13 @@
+[metadata]
+name = puppet-nova
+summary = Puppet module for OpenStack Nova
+description-file =
+    README.md
+author = Puppet Labs and OpenStack Contributors
+author-email = openstack-dev@lists.openstack.org
+home-page = http://www.openstack.org/
+classifier =
+    Intended Audience :: Developers
+    Intended Audience :: System Administrators
+    License :: OSI Approved :: Apache Software License
+    Operating System :: POSIX :: Linux