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/network_plugin/canal/tasks/main.yml

@@ -0,0 +1,27 @@
+---
+- name: Canal | Write flannel configuration
+  template:
+    src: network.json.j2
+    dest: /etc/flannel-network.json
+    backup: yes
+
+- name: Canal | Write canal configuration
+  template:
+    src: canal-node.yml.j2
+    dest: /etc/kubernetes/canal-node.yaml
+
+- name: Canal | Copy cni plugins from hyperkube
+  command: "/usr/bin/docker run --rm -v /opt/cni/bin:/cnibindir {{ hyperkube_image_repo }}:{{ hyperkube_image_tag }} /usr/bin/rsync -a /opt/cni/bin/ /cnibindir/"
+  register: cni_task_result
+  until: cni_task_result.rc == 0
+  retries: 4
+  delay: "{{ retry_stagger | random + 3 }}"
+  changed_when: false
+
+- name: Canal | Copy cni plugins from calico/cni
+  command: "/usr/bin/docker run --rm -v /opt/cni/bin:/cnibindir {{ calico_cni_image_repo }}:{{ calico_cni_image_tag }} sh -c 'cp -a /opt/cni/bin/* /cnibindir/'"
+  register: cni_task_result
+  until: cni_task_result.rc == 0
+  retries: 4
+  delay: "{{ retry_stagger | random + 3 }}"
+  changed_when: false