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
Make 101-tuskar-ui re-runnable

The checks that are added are:
* if a Tuskar overcloud plan already exists, skip the tuskar API
  calls
* do not update the openstack_dashboard settings if the specified
  settings are already present

Change-Id: Idedfd2dea2a823245e749ae27e40ae4e29639726
Merge "Install openstackclient"