Sets IgnoreUnknown=1 in CNI_ARGS

K8 uses CNI_ARGS to pass pod namespace, name and infra container
id to the CNI network plugin. CNI logic will throw an error
if these args are not known to it, unless the user specifies
IgnoreUnknown as part of CNI_ARGS. This PR sets IgnoreUnknown=1
to prevent the CNI logic from erroring and blocking pod setup.
https://github.com/appc/cni/pull/158
https://github.com/appc/cni/issues/126

pkg/kubelet/network/cni/cni.go

@@ -197,6 +197,7 @@ func buildCNIRuntimeConf(podName string, podNs string, podInfraContainerID kubec
 		NetNS:       podNetnsPath,
 		IfName:      network.DefaultInterfaceName,
 		Args: [][2]string{
+			{"IgnoreUnknown", "1"},
 			{"K8S_POD_NAMESPACE", podNs},
 			{"K8S_POD_NAME", podName},
 			{"K8S_POD_INFRA_CONTAINER_ID", podInfraContainerID.ID},