Remove signal handler registration from pkg/kubelet

The goal of this change is to remove the registration of signal
handling from pkg/kubelet. We now pass in a stop channel.

If you register a signal handler in `main()` to aid in a controlled
and deliberate exit then the handler registered in `pkg/kubelet` often
wins and the process exits immediately. This means all other signal
handler registrations are currently racy if `DockerServer.Start()` is
directly or indirectly invoked.

This change also removes another signal handler registration from
`NewAPIServerCommand()`; a stop channel is now passed to this
function.

cmd/kubelet/kubelet.go

@@ -26,6 +26,7 @@ import (
 	"os"
 	"time"
 
+	"k8s.io/apiserver/pkg/server"
 	"k8s.io/apiserver/pkg/util/logs"
 	"k8s.io/kubernetes/cmd/kubelet/app"
 	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
@@ -35,7 +36,7 @@ import (
 func main() {
 	rand.Seed(time.Now().UTC().UnixNano())
 
-	command := app.NewKubeletCommand()
+	command := app.NewKubeletCommand(server.SetupSignalHandler())
 	logs.InitLogs()
 	defer logs.FlushLogs()