Ansible 2.4 changes the way includes work. Now you have to use "import"
for playbooks and tasks that are static, and "include" for those that
are dynamic (ie, those that use variables, loops, etc).
See: http://docs.ansible.com/ansible/devel/playbooks_reuse_includes.html
Debian 9 is still in beta and doesn't have nginx.org builds yet, so
we need to use the nginx package in Debian's repositories, and that
required a bit of a different configuration.
After official nginx.org builds are released we can revert this.
