Add pylint to depot_tools.

pylint.py

Index: pylint.py
diff --git a/pylint.py b/pylint.py
new file mode 100644
index 0000000000000000000000000000000000000000..9caa3a37110e19e8c0a435a2db78c3939513a310
--- /dev/null
+++ b/pylint.py
@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+# Copyright (c) 2012 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.
+
+"""A wrapper script for using pylint from the command line."""
+
+import os
+import subprocess
+import sys
+
+
+_HERE = os.path.dirname(os.path.abspath(__file__))
+_PYLINT = os.path.join(_HERE, 'third_party', 'pylint.py')
+_RC_FILE = os.path.join(_HERE, 'pylintrc')
+
+
+# Run pylint. We prepend the command-line with the depot_tools rcfile. If
+# another rcfile is to be used, passing --rcfile a second time on the command-
+# line will work fine.
+command = [sys.executable, _PYLINT, '--rcfile=%s' % _RC_FILE] + sys.argv[1:]
+sys.exit(subprocess.call(command))