another kubelet_args fix

roles/openshift_node/templates/node.yaml.v1.j2

@@ -9,7 +9,7 @@ imageConfig:
   latest: false
 kind: NodeConfig
 {% if openshift.node.kubelet_args is defined and openshift.node.kubelet_args %}
-kubeletArguments: {{ openshift.node.kubelet_args }}
+kubeletArguments: {{ openshift.node.kubelet_args | to_json }}
 {% endif %}
 masterKubeConfig: system:node:{{ openshift.common.hostname }}.kubeconfig
 networkPluginName: {{ openshift.common.sdn_network_plugin_name }}