Add Ansible role to fix Drupal file permissions

Add a new `drupal-permissions` Ansible role that resets the file and
directory permissions to match the ones described in
https://www.drupal.org/node/244924.

This will later be released to Ansible Galaxy, but for now it will
remain in this repository until the required changes are made and the
appropriate documentation is added.

Fixes #191

tools/ansible/deploy/after-symlink-shared.yml

@@ -1,10 +0,0 @@
----
-- name: Setup directory permissions for files directories
-  become: true
-  file:
-    path: '{{ ansistrano_shared_path }}/{{ project_web_dir }}/sites/default/files'
-    state: directory
-    owner: www-data
-    group: root
-    mode: u=rwx,g=rw,o=
-    recurse: true

tools/ansible/deploy/after-update-code.yml

@@ -9,6 +9,10 @@
   include_role:
     name: opdavies.drupal_settings_files
 
+- name: Fix file permissions
+  include_role:
+    name: drupal-permissions
+
 - name: Clear Drush cache
   command: >
     {{ release_drush_path }}