Add DefaultAddress to client

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/containerd/config_linux.go

@@ -1,10 +1,12 @@
 package main
 
+import "github.com/containerd/containerd"
+
 func defaultConfig() *config {
 	return &config{
 		Root: "/var/lib/containerd",
 		GRPC: grpcConfig{
-			Address: "/run/containerd/containerd.sock",
+			Address: containerd.DefaultAddress,
 		},
 		Debug: debug{
 			Level:   "info",

cmd/ctr/main.go

@@ -5,6 +5,7 @@ import (
 	"os"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/containerd/containerd"
 	"github.com/containerd/containerd/version"
 	"github.com/urfave/cli"
 )
@@ -38,7 +39,7 @@ containerd CLI
 		cli.StringFlag{
 			Name:  "address, a",
 			Usage: "address for containerd's GRPC server",
-			Value: "/run/containerd/containerd.sock",
+			Value: containerd.DefaultAddress,
 		},
 		cli.DurationFlag{
 			Name:  "timeout",