Update to Ansible 2.0
Ansible 2.0 was released a month ago and comes with a few backwards incompatible changes. Eventually we should move to it, and ideally with the entire ansible-servers stack in one go (although that will require some coordination).
I propose to test all our playbooks with Ansible 2.0 individually, make any changes (if necessary) in ansible-2 branches, and then update the ansible-servers repository.