Update with_items loops to use new-ish "loop" keyword

Ansible 2.4 and 2.5 are moving away from specialized loop functions
and the old syntax will eventually be deprecated and removed. I did
not change the with_fileglob loops because I'm not sure about their
syntax yet.

See: https://docs.ansible.com/ansible/latest/user_guide/playbooks_loops.html

roles/nginx/tasks/main.yml

@@ -19,7 +19,7 @@
 
 - name: Copy extra nginx configs
   copy: src={{ item }} dest=/etc/nginx/{{ item }} mode=0644 owner=root group=root
-  with_items:
+  loop:
     - extra-security.conf
     - fastcgi_cache
   notify: