Merge remote-tracking branch 'leekchan/set_cookie_expires_days'

Conflicts:
	tornado/test/web_test.py

diff --cc tornado/test/web_test.py
index 149b479557620ad19adffa9c20df29bfcc807b4b,0110590f1a900a95c6b8990c4e742e19fc521f5e..b984ac4a79a51a1236adbddfc5823f6024c5d1af
--- 1/tornado/test/web_test.py
--- 2/tornado/test/web_test.py
+++ b/tornado/test/web_test.py
@@@ -10,8 -10,8 +10,8 @@@ from tornado.simple_httpclient import S
  from tornado.template import DictLoader
  from tornado.testing import AsyncHTTPTestCase, ExpectLog, gen_test
  from tornado.test.util import unittest
- from tornado.util import u, ObjectDict, unicode_type
+ from tornado.util import u, ObjectDict, unicode_type, timedelta_to_seconds
 -from tornado.web import RequestHandler, authenticated, Application, asynchronous, url, HTTPError, StaticFileHandler, _create_signature_v1, create_signed_value, decode_signed_value, ErrorHandler, UIModule, MissingArgumentError, stream_request_body, Finish
 +from tornado.web import RequestHandler, authenticated, Application, asynchronous, url, HTTPError, StaticFileHandler, _create_signature_v1, create_signed_value, decode_signed_value, ErrorHandler, UIModule, MissingArgumentError, stream_request_body, Finish, removeslash, addslash
  
  import binascii
  import contextlib