Install additional pacakges into venvs
Install additional pacakges into venvs

Populate ADDITIONAL_VENV_PACKAGES on target side so venvs get
the packages they need.

Depends-On: I9cf298b936fd10c95e2ce5f51aab0d49d4b7f37f
Change-Id: Icc324fe6b0a8464027a624f9773030d08ca7c176

dtroyer/grenade,openstack-dev/grenade,openstack-dev/grenade,dtroyer/grenade