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/upgrade/post-upgrade/tasks/main.yml

@@ -1,7 +1,5 @@
 ---
-
 - name: Uncordon node
   command: "{{ bin_dir }}/kubectl uncordon {{ inventory_hostname }}"
   delegate_to: "{{ groups['kube-master'][0] }}"
   when: (needs_cordoning|default(false)) and ( {%- if inventory_hostname in groups['kube-node'] -%} true {%- else -%} false {%- endif -%} )
-

roles/upgrade/pre-upgrade/defaults/main.yml

@@ -1,3 +1,3 @@
+---
 drain_grace_period: 90
 drain_timeout: 120s
-