Build os-cloud-config in setup-clienttools

os-cloud-config is going to start including CLI scripts that
devtest will start calling. Install os-cloud-config into the
openstack-tools venv so that scripts are installed.

Change-Id: Ib51197b1ad4e1a46f04a677be17d8e9c6cc530cb
Merge "Build os-cloud-config in setup-clienttools"