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>

tools/clusterdevel/start_minishift_dev.yml

@@ -8,4 +8,4 @@
     - awx_task_cpu_request: 500
     - awx_task_mem_request: 512
   roles:
-    - { role: minishift }
+    - {role: minishift}