switched to go-mod, updated codegangsta/cli -> urfave/cli

vendor/github.com/kr/pty/README.md

@@ -1,36 +1,9 @@
 # pty
 
-Pty is a Go package for using unix pseudo-terminals.
+This Go module has moved to <https://github.com/creack/pty>.
 
-## Install
+Existing clients will continue to work.
 
-    go get github.com/kr/pty
+New clients should use the new module import path
+`github.com/creack/pty`.
 
-## Example
-
-```go
-package main
-
-import (
-	"github.com/kr/pty"
-	"io"
-	"os"
-	"os/exec"
-)
-
-func main() {
-	c := exec.Command("grep", "--color=auto", "bar")
-	f, err := pty.Start(c)
-	if err != nil {
-		panic(err)
-	}
-
-	go func() {
-		f.Write([]byte("foo\n"))
-		f.Write([]byte("bar\n"))
-		f.Write([]byte("baz\n"))
-		f.Write([]byte{4}) // EOT
-	}()
-	io.Copy(os.Stdout, f)
-}
-```