ansible_hostname is not used within any tasks and, by default, is the
same value as container_name.
ansible_ssh_host and container_address are also the same value by
default, both are assigned to hosts through the dynamic inventory script.
Additionally, overriding ansible_ssh_host through playbook vars breaks
tasks that delegate to other hosts when using Ansible2.
Change-Id: I2525b476c9302ef37f29e2beb132856232d129e2
bcbc5b27fc