added a note like the following to each file hit with unlabled 2.0 changes...
Ansible 2.0 moved away from using ansible_ssh_* variables to accepting
ansible_* variables. If you are using a version of Ansible prior to 2.0,
you should continue using the older style variables (ansible_ssh_*), such
as ansible_ssh_user instead of ansible_user and ansible_ssh_port instead of
ansible_port, which appear in the following content. These shorter variables
are ignored, without warning, in older versions of Ansible.