Change to go1.6.1 and vendoring

vendor/github.com/kr/pty/run.go

@@ -0,0 +1,28 @@
+package pty
+
+import (
+	"os"
+	"os/exec"
+	"syscall"
+)
+
+// Start assigns a pseudo-terminal tty os.File to c.Stdin, c.Stdout,
+// and c.Stderr, calls c.Start, and returns the File of the tty's
+// corresponding pty.
+func Start(c *exec.Cmd) (pty *os.File, err error) {
+	pty, tty, err := Open()
+	if err != nil {
+		return nil, err
+	}
+	defer tty.Close()
+	c.Stdout = tty
+	c.Stdin = tty
+	c.Stderr = tty
+	c.SysProcAttr = &syscall.SysProcAttr{Setctty: true, Setsid: true}
+	err = c.Start()
+	if err != nil {
+		pty.Close()
+		return nil, err
+	}
+	return pty, err
+}