Adding support for canal network plugin

This patch provides support for Canal network plugin installation
as a self-hosted app, see the following link for details:

https://github.com/tigera/canal/tree/master/k8s-install

roles/kubernetes-apps/network_plugin/canal/tasks/main.yaml

@@ -0,0 +1,8 @@
+- name: Start flannel and calico-node
+  run_once: true
+  kube:
+    name: "canal-node"
+    kubectl: "{{bin_dir}}/kubectl"
+    filename: "/etc/kubernetes/canal-node.yaml"
+    resource: "ds"
+    namespace: "kube-system"

roles/kubernetes-apps/network_plugin/meta/main.yml

@@ -0,0 +1,4 @@
+---
+dependencies:
+ - role: kubernetes-apps/network_plugin/canal
+   when: kube_network_plugin == 'canal'