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/defaults/main.yml

@@ -63,7 +63,7 @@ vault_needs_gen: false
 vault_port: 8200
 # Although "cert" is an option, ansible has no way to auth via cert until
 # upstream merges: https://github.com/ansible/ansible/pull/18141
-vault_role_auth_method: userpass 
+vault_role_auth_method: userpass
 vault_roles:
   - name: etcd
     group: etcd