Add sshchat dependencies in vendor

vendor/github.com/shazow/rateio/writer.go

@@ -0,0 +1,25 @@
+package rateio
+
+import "io"
+
+type writer struct {
+	io.Writer
+	Limiter
+}
+
+// Write writes the contents of p into the buffer.
+// Returns ErrRateExceeded error if our specified read is exceeded.
+func (w *writer) Write(p []byte) (n int, err error) {
+	n, err = w.Writer.Write(p)
+	if err != nil {
+		return
+	}
+
+	err = w.Limiter.Count(n)
+	return
+}
+
+// NewWriter proxies an io.Writer but keeps track of bytes read based on our Limiter.
+func NewWriter(w io.Writer, limiter Limiter) io.Writer {
+	return &writer{w, limiter}
+}