Use cobra in skopeo

Use cobra in skopeo can help share code with podman/buildah(code for skopeo login/logout CLI).
(libpod issue  #839)

Signed-off-by: Qi Wang <qiwan@redhat.com>

vendor/github.com/spf13/cobra/command_win.go

@@ -0,0 +1,26 @@
+// +build windows
+
+package cobra
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/inconshreveable/mousetrap"
+)
+
+var preExecHookFn = preExecHook
+
+func preExecHook(c *Command) {
+	if MousetrapHelpText != "" && mousetrap.StartedByExplorer() {
+		c.Print(MousetrapHelpText)
+		if MousetrapDisplayDuration > 0 {
+			time.Sleep(MousetrapDisplayDuration)
+		} else {
+			c.Println("Press return to continue...")
+			fmt.Scanln()
+		}
+		os.Exit(1)
+	}
+}