Variables which were not used at all or were used only within a single
role and were unchanged from that role's defaults have been removed.
Variables which were used only within a playbook or overrode role
defaults and were only relevant to hosts applying that playbook or role
have been moved into a new file for the host group.
Variables which are required across multiple host groups through
playbooks or roles have been moved to all.yml. The host.yml and
all_containers.yml files have been removed.
Change-Id: If31f0ff7ca34b0e95a5a86876ec9330dae31a4aa
d59a2ffd62