Replace stringid with simple rand reader

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

cmd/ctr/main.go

@@ -18,13 +18,19 @@ package main
 
 import (
 	"fmt"
+	"math/rand"
 	"os"
+	"time"
 
 	ctrapp "github.com/containerd/containerd/cmd/ctr/app"
 
 	cricli "github.com/containerd/cri/cli"
 )
 
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
 func main() {
 	app := ctrapp.New()
 	app.Commands = append(app.Commands, cricli.Command)