[rally] Install rally-openstack package
[rally] Install rally-openstack package

Latest rally version (1.0.0) moved all the plugins to a separated
repository. The plugins are contained in rally-openstack pip
package. Let's install the pip package (I did not find direct
way how to install it from git directly).

The rpm package is couple of verions behind so It still includes
core and plugins code. Not sure how the packaging will be done but
that must be solved later, It works okay for now.

Change-Id: Ifad868f35048241737c3c3e5edf4a0ead022f373

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared