Re-order template deploy & add validate:

Re-ordering the tasks in this way (having the vhosts deployed first)
allows the 'validate' param to collectively check the deployed Nginx config.

Deploying vhosts after makes it hard to check their validity, as Nginx's
config checking will operate on a "master" configuration that includes
others (checking those included, also) but would error out when checking
these individual configs if they do not contain a fully working Nginx
config (which they often don't, due to their nature).

tasks/main.yml

@@ -15,6 +15,9 @@
 - include: setup-Debian.yml
   when: ansible_os_family == 'Debian'
 
+# Vhost configuration
+- include: vhosts.yml
+
 # Nginx setup.
 - name: Copy nginx configuration in place.
   template:
@@ -23,9 +26,8 @@
     owner: root
     group: root
     mode: 0644
+  validate: 'nginx -t -c %s'
   notify: restart nginx
 
 - name: Ensure nginx is started and enabled to start at boot.
   service: name=nginx state=started enabled=yes
-
-- include: vhosts.yml