Use nginx-extras for http2 support

roles/service-nginx/tasks/nginx.yml

@@ -1,6 +1,6 @@
 ---
 - name: ensure nginx is installed
-  apt: name=nginx-full state=latest default_release={{ ansible_distribution_release }}-backports install_recommends=no
+  apt: name=nginx-extras state=latest default_release={{ ansible_distribution_release }}-backports install_recommends=no
 
 - name: ensure nginx default configuration is disabled
   file: name=/etc/nginx/sites-enabled/default state=absent