PRESUBMIT: Improve PyLint check and add GN format check.

Add pylintrc file based on
https://code.google.com/p/chromium/codesearch#chromium/src/tools/perf/pylintrc
bit tightened up quite a bit (the one in depot_tools is far
more relaxed).

Remove a few excluded directories from pylint check and fixed/
suppressed all warnings generated.

Add GN format check + formatted all GN files using 'gn format'.
Cleanup redundant rules in tools/PRESUBMIT.py

TESTED=Ran 'git cl presubmit -vv', fixed the PyLint violations.
Ran it again with a modification in webrtc/build/webrtc.gni, formatted
all the GN files and ran it again.

R=henrika@webrtc.org, phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/50069004

Cr-Commit-Position: refs/heads/master@{#9274}
diff --git a/tools/perf/perf_utils.py b/tools/perf/perf_utils.py
index 77eda1e..3d3cb10 100644
--- a/tools/perf/perf_utils.py
+++ b/tools/perf/perf_utils.py
@@ -1,6 +1,12 @@
-# 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.
+#!/usr/bin/env python
+#
+# Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
 
 # Copied from /src/chrome/test/pyautolib/pyauto_utils.py in Chromium.
 
@@ -28,4 +34,4 @@
   print '%sRESULT %s: %s= %s %s' % (
       waterfall_indicator, graph_name, series_name,
       str(data_point).replace(' ', ''), units)
-  sys.stdout.flush()
\ No newline at end of file
+  sys.stdout.flush()