Use python3 for running Ansible in init

Use python3 for running Ansible in init

Because the python docker container installs python to a location other
than /usr/bin, ansible doesn't know it have python3 available. Setting
this flag allows the build to use python3 and fix a pip error.

An extra setting ANSIBLE_STDOUT_CALLBACK=yaml is added to add clearer
output when running ansible, and can be overridden in the
docker-compose.yaml file.

Change-Id: I9dfc1aa0be17fb93d73e3ce321330558b44f7829
Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>