Change calicoctl deployment to use container

Improves upgradability of calicoctl by leveraging docker tags.

roles/network_plugin/calico/defaults/main.yml

@@ -4,3 +4,5 @@ nat_outgoing: true
 
 # cloud_provider can only be set to 'gce' or 'aws'
 # cloud_provider:
+calicoctl_image_repo: calico/ctl
+calicoctl_image_tag: "{{ calico_version }}"