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/kubernetes-apps/ansible/tasks/netchecker.yml

@@ -1,3 +1,4 @@
+---
 - name: Kubernetes Apps | Lay Down Netchecker Template
   template:
     src: "{{item.file}}"
@@ -24,7 +25,7 @@
     state: absent
   when: inventory_hostname == groups['kube-master'][0]
 
-#FIXME: remove if kubernetes/features#124 is implemented
+# FIXME: remove if kubernetes/features#124 is implemented
 - name: Kubernetes Apps | Purge old Netchecker daemonsets
   kube:
     name: "{{item.item.name}}"