Adding yamllinter to ci steps (#1556)

* Adding yaml linter to ci check

* Minor linting fixes from yamllint

* Changing CI to install python pkgs from requirements.txt

- adding in a secondary requirements.txt for tests
- moving yamllint to tests requirements

roles/vault/tasks/shared/find_leader.yml

@@ -15,7 +15,7 @@
     vault_leader_url: "{{ vault_config.listener.tcp.tls_disable|d()|ternary('http', 'https') }}://{{ item }}:{{ vault_port }}"
   with_items: "{{ groups.vault }}"
   when: "hostvars[item]['vault_leader_check'].get('status') in [200,503]"
-  #run_once: true
+  # run_once: true
 
 - name: find_leader| show vault_leader_url
   debug: var=vault_leader_url verbosity=2