Show team and repo badges on README

This patch adds the team's and repository's badges to the README file.
The motivation behind this is to communicate the project status and
features at first glance.

For more information about this effort, please read this email thread:

http://lists.openstack.org/pipermail/openstack-dev/2016-October/105562.html

To see an example of how this would look like check:

https://gist.github.com/30af7c8ad287756d38d131d1f5dceae0

Change-Id: I2d906fa0675463e21f2786d93f464c465f2bc3b1

README.rst

@@ -1,3 +1,12 @@
+========================
+Team and repository tags
+========================
+
+.. image:: http://governance.openstack.org/badges/python-openstackclient.svg
+    :target: http://governance.openstack.org/reference/tags/index.html
+
+.. Change things from this point on
+
 ===============
 OpenStackClient
 ===============