Move docker systemd unit creation to docker role

Creating the unit using default settings early on
and then changing it during network_plugin section
leads to too many docker restarts and duplicated code.

Reversed Wants= dependence on docker.service so it does not
restart docker when reloading systemd

Consolidated all docker restart handlers.

roles/network_plugin/flannel/handlers/main.yml

@@ -4,22 +4,6 @@
   ignore_errors: yes
   notify: restart docker
 
-- name: restart docker
-  command: /bin/true
-  notify:
-    - Flannel | reload systemd
-    - Flannel | reload docker
-    - Flannel | reload kubelet
-
-- name : Flannel | reload systemd
-  shell: systemctl daemon-reload
-  when: ansible_service_mgr == "systemd"
-
-- name: Flannel | reload docker
-  service:
-    name: docker
-    state: restarted
-
 - name: Flannel | reload kubelet
   service:
     name: kubelet