Containerd client integration

This commit:
1) Replaces the usage of containerd GRPC APIs with the containerd client for all operations related to containerd.
2) Updated containerd to v1.0alpha4+
3) Updated runc to v1.0.0

Signed-off-by: Abhinandan Prativadi <abhi@docker.com>

pkg/server/status.go

@@ -20,7 +20,6 @@ import (
 	"fmt"
 
 	"golang.org/x/net/context"
-	healthapi "google.golang.org/grpc/health/grpc_health_v1"
 
 	"k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
 )
@@ -38,9 +37,8 @@ func (c *criContainerdService) Status(ctx context.Context, r *runtime.StatusRequ
 		Type:   runtime.RuntimeReady,
 		Status: true,
 	}
-	// Use containerd grpc server healthcheck service to check its readiness.
-	resp, err := c.healthService.Check(ctx, &healthapi.HealthCheckRequest{})
-	if err != nil || resp.Status != healthapi.HealthCheckResponse_SERVING {
+	serving, err := c.client.IsServing(ctx)
+	if err != nil || !serving {
 		runtimeCondition.Status = false
 		runtimeCondition.Reason = runtimeNotReadyReason
 		if err != nil {
@@ -49,7 +47,6 @@ func (c *criContainerdService) Status(ctx context.Context, r *runtime.StatusRequ
 			runtimeCondition.Message = "Containerd grpc server is not serving"
 		}
 	}
-
 	networkCondition := &runtime.RuntimeCondition{
 		Type:   runtime.NetworkReady,
 		Status: true,