Change Rietveld.add_comment() to not add the user as a reviewer by default

This is mainly to reduce the spam that the commit queue adds to
commit-bot@chromium.org as all follow up emails on code reviews are sent to it
because it was adding itself as a reviewer, even if it is not.

R=rogerta@chromium.org
BUG=


Review URL: https://chromiumcodereview.appspot.com/10918075

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@155141 0039d316-1c4b-4281-b951-d872f2087c98

rietveld.py

@@ -226,7 +226,7 @@ class Rietveld(object):
         ('description', description),
         ('xsrf_token', self.xsrf_token())])
 
-  def add_comment(self, issue, message):
+  def add_comment(self, issue, message, add_as_reviewer=False):
     max_message = 10000
     tail = '…\n(message too large)'
     if len(message) > max_message:
@@ -236,6 +236,7 @@ class Rietveld(object):
         ('xsrf_token', self.xsrf_token()),
         ('message', message),
         ('message_only', 'True'),
+        ('add_as_reviewer', str(bool(add_as_reviewer))),
         ('send_mail', 'True'),
         ('no_redirect', 'True')])