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/network_plugin/weave/tasks/main.yml

@@ -1,4 +1,5 @@
-#FIXME: remove if kubernetes/features#124 is implemented
+---
+# FIXME: remove if kubernetes/features#124 is implemented
 - name: Weave | Purge old weave daemonset
   kube:
     name: "weave-net"
@@ -9,7 +10,6 @@
     state: absent
   when: inventory_hostname == groups['kube-master'][0] and weave_manifest.changed
 
-
 - name: Weave | Start Resources
   kube:
     name: "weave-net"
@@ -21,7 +21,6 @@
   with_items: "{{ weave_manifest.changed }}"
   when: inventory_hostname == groups['kube-master'][0]
 
-
 - name: "Weave | wait for weave to become available"
   uri:
     url: http://127.0.0.1:6784/status