yamllint: Make all files in awx pass yamllint

This commit updates all files that weren't passing yamllint for them to
pass.

A new yamllint target has been added. One can run `tox -e yamllint` or
`yamllint -s .` locally to ensure yaml files are still passing.

This check will be enabled in the CI so it can get on every new
contributions, and prevent merging non-compliant code.

Signed-off-by: Yanis Guenane <yguenane@redhat.com>

installer/roles/local_docker/defaults/main.yml

@@ -18,4 +18,3 @@ memcached_image: "memcached"
 memcached_version: "alpine"
 memcached_hostname: "memcached"
 memcached_port: "11211"
-

installer/roles/local_docker/tasks/main.yml

@@ -17,7 +17,7 @@
   file:
     state: directory
     path: "{{ item }}"
-    recurse: yes
+    recurse: true
   when: upgrade_postgres | bool
   with_items:
     - "{{ postgres_data_dir }}/10/data"
@@ -25,7 +25,7 @@
 - name: Stop AWX before upgrading postgres
   docker_service:
     project_src: "{{ docker_compose_dir }}"
-    stopped: yes
+    stopped: true
   when: upgrade_postgres | bool
 
 - name: Upgrade Postgres