Remove unused install_venv_common from openstack-common.conf

Change-Id: I92be714114161c324dcee0db2a55f3b212570b7f
Add apiclient module from oslo-incubator

This code was pulled from oslo-incubator at commit
73bd293303e2360a3ea0d0e4d4af1618eb15d96e.

blueprint command-line

Change-Id: Ie768918b84cd561c918a7b6367fcc64f825efbc2