Fix Ansible 2.8 deprecation warnings for bare vars.

tasks/setup-RedHat.yml

@@ -6,7 +6,7 @@
     owner: root
     group: "{{ root_group }}"
     mode: 0644
-  when: nginx_yum_repo_enabled
+  when: nginx_yum_repo_enabled | bool
 
 - name: Ensure nginx is installed.
   package:

tasks/setup-Ubuntu.yml

@@ -5,7 +5,7 @@
     state: present
     update_cache: true
   register: nginx_ppa_added
-  when: nginx_ppa_use
+  when: nginx_ppa_use | bool
 
 - name: Ensure nginx will reinstall if the PPA was just added.
   apt:

tasks/vhosts.yml

@@ -3,7 +3,7 @@
   file:
     path: "{{ nginx_default_vhost_path }}"
     state: absent
-  when: nginx_remove_default_vhost
+  when: nginx_remove_default_vhost | bool
   notify: restart nginx
 
 - name: Ensure nginx_vhost_path exists.