Leave dhcpcd (and netconf) running in the background.

Add wait-for-network.

cmd/waitfornetwork/waitfornetwork.go

@@ -0,0 +1,23 @@
+package waitfornetwork
+
+import (
+	"github.com/rancher/os/cmd/network"
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+func handleTerm() {
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, syscall.SIGTERM)
+	<-c
+	os.Exit(0)
+}
+
+func Main() {
+	go handleTerm()
+	if _, err := os.Stat(network.NETWORK_DONE); err == nil {
+		os.Exit(0)
+	}
+	select {}
+}