Add cros-gunzip-dd.py to allow write gziped images to a device on ChromeOS

Avoiding the use of `dd` (crashing command).

cros-gunzip-dd.py

+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+"""
+  Usage: cros-gunzip-dd.py SRC.gz DEST
+
+  It's a shortcut for `zcat SRC.gz | dd of=DEST`. Useful on nayuos because the
+  "dd" command may crash.
+"""
+import sys, gzip
+src = gzip.open(sys.argv[1], "rb")
+dst = open(sys.argv[2], "wb")
+while True:
+  buf = src.read(512)
+  if len(buf) == 0:
+    break
+  dst.write(buf)