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}

setup_links.py

@@ -171,7 +171,7 @@ class Remove(Action):
     else:
       log('Removing %s: %s', filesystem_type, self._path)
 
-  def doit(self, _links_db):
+  def doit(self, _):
     os.remove(self._path)
 
 
@@ -187,7 +187,7 @@ class Rmtree(Action):
     else:
       logging.warn('Removing directory: %s', self._path)
 
-  def doit(self, _links_db):
+  def doit(self, _):
     if sys.platform.startswith('win'):
       # shutil.rmtree() doesn't work on Windows if any of the directories are
       # read-only, which svn repositories are.
@@ -202,7 +202,7 @@ class Makedirs(Action):
     self._priority = 1
     self._path = path
 
-  def doit(self, _links_db):
+  def doit(self, _):
     try:
       os.makedirs(self._path)
     except OSError as e:
@@ -258,7 +258,7 @@ if sys.platform.startswith('win'):
   os.symlink = symlink
 
 
-class WebRTCLinkSetup():
+class WebRTCLinkSetup(object):
   def __init__(self, links_db, force=False, dry_run=False, prompt=False):
     self._force = force
     self._dry_run = dry_run
@@ -482,7 +482,7 @@ def main():
       logging.error('On Windows, you now need to have administrator '
                     'privileges for the shell running %s (or '
                     '`gclient sync|runhooks`).\nPlease start another command '
-                    'prompt as Administrator and try again.' % sys.argv[0])
+                    'prompt as Administrator and try again.', sys.argv[0])
       return 1
 
   if not os.path.exists(CHROMIUM_CHECKOUT):