Install openstackclient

KeystoneClient doesn't support keystone v3 operations.
They are now supported by openstackclient. In order to
use keystone v3 operations we need to have
python-openstackclient installed

Change-Id: I8112e387180aa88bc92d91e103ee958f7bf56b9a
Closes-bug: #1384838
Merge "Install openstackclient"