Perform upgrade by default when installing ansible
Perform upgrade by default when installing ansible

We don't upgrade ansible in the upgrade jobs because the requirement is
already satisfied according to pip.
Although, we should upgrade ansible as it may differ between releases.
Also perform a clean install if ansible is already present to avoid
conflicts.

Change-Id: I3cb1059408ef069001cde91474c68768315ff784

openstack/bifrost,openstack/bifrost