Add yapf

Add yapf and yapf.bat with a vpython spec, so it can be used anywhere, e.g.
bots.

Change-Id: I363c0251ed766b2bb15a8c0f03615bc9a3ecb37a
Reviewed-on: https://chromium-review.googlesource.com/1107170
Commit-Queue: Nodir Turakulov <nodir@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>

.gitattributes

@@ -24,6 +24,7 @@
 /pylint*                      recipes
 /repo                         recipes
 /roll-dep*                    recipes
+/yapf*                        recipes
 
 # Symlinks
 /cbuildbot      recipes

yapf

+#!/usr/bin/env vpython
+
+# [VPYTHON:BEGIN]
+# wheel: <
+#   name: "infra/python/wheels/yapf-py2_py3"
+#   version: "version:0.22.0"
+# >
+# [VPYTHON:END]
+
+# -*- coding: utf-8 -*-
+import re
+import sys
+
+from yapf import run_main
+
+if __name__ == '__main__':
+    sys.exit(run_main())

yapf.bat

+@echo off
+:: Copyright (c) 2015 The Chromium Authors. All rights reserved.
+:: Use of this source code is governed by a BSD-style license that can be
+:: found in the LICENSE file.
+setlocal
+
+:: Ensure that "depot_tools" is somewhere in PATH so this tool can be used
+:: standalone, but allow other PATH manipulations to take priority.
+set PATH=%PATH%;%~dp0
+
+:: Defer control.
+python "%~dp0\yapf" %*