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/docker/templates/systemd-docker.service.j2

@@ -0,0 +1,40 @@
+[Unit]
+Description=Docker Application Container Engine
+Documentation=http://docs.docker.com
+{% if ansible_os_family == "RedHat" %}
+After=network.target docker-storage-setup.service
+Wants=docker-storage-setup.service
+{% elif ansible_os_family == "Debian" %}
+After=network.target docker.socket
+Wants=docker.socket
+{% endif %}
+
+[Service]
+Type=notify
+{% if ansible_os_family == "RedHat" %}
+EnvironmentFile=-/etc/default/docker
+EnvironmentFile=-/etc/sysconfig/docker
+EnvironmentFile=-/etc/sysconfig/docker-network
+EnvironmentFile=-/etc/sysconfig/docker-storage
+{% elif ansible_os_family == "Debian" %}
+EnvironmentFile=-/etc/default/docker
+{% endif %}
+Environment=GOTRACEBACK=crash
+ExecReload=/bin/kill -s HUP $MAINPID
+Delegate=yes
+KillMode=process
+ExecStart=/usr/bin/docker daemon \
+          $OPTIONS \
+          $DOCKER_STORAGE_OPTIONS \
+          $DOCKER_NETWORK_OPTIONS \
+          $INSECURE_REGISTRY \
+          $DOCKER_OPTS
+TasksMax=infinity
+LimitNOFILE=1048576
+LimitNPROC=1048576
+LimitCORE=infinity
+TimeoutStartSec=1min
+Restart=on-abnormal
+
+[Install]
+WantedBy=multi-user.target