Merge remote-tracking branch 'rgbkrk/cross_origin' into merge

diff --cc docs/overview.rst
Simple merge

diff --cc tornado/test/websocket_test.py
Simple merge

diff --cc tornado/websocket.py
index bfb90d180d24dfed9428949a4614543dfa16efc0,6f552f71d03117bb4a443b6e35299e03a11e9d90..d797a0cd2025d81b33ecfdb5931927bdfa1d9117
--- 1/tornado/websocket.py
--- 2/tornado/websocket.py
+++ b/tornado/websocket.py
@@@ -37,10 -37,15 +37,15 @@@ from tornado import httpclient, httputi
  from tornado.ioloop import IOLoop
  from tornado.iostream import StreamClosedError
  from tornado.log import gen_log, app_log
 -from tornado.netutil import Resolver
  from tornado import simple_httpclient
 +from tornado.tcpclient import TCPClient
  from tornado.util import bytes_type, unicode_type
  
+ try:
+     from urllib.parse import urlparse # py2
+ except ImportError:
+     from urlparse import urlparse # py3
+ 
  try:
      xrange  # py2
  except NameError: