Crude fix for issue #855: automatically initiate SSL handshake in SSLIOStream.
Perhaps this should be exposed as an option instead?
Route all callback error logging in IOLoop through handle_callback_exception.
Clear the IOStream buffers on close even when there is no close callback.

Closes #828. (again)
RequestHandler sets its close callback on the HTTPConnection, not the IOStream.

Fixes a bug in which close callbacks would never be called for subsequent
requests on a reused connection.
Merge remote-tracking branch 'pitrou/issue855-ssl-auto-handshake'
Less crude fix for #855: only do anything for already-connected sockets.
Allow deleting all cookies on custom domains
Update ca-certificates.crt to the current Mozilla version.

This file was generated by downloading
https://mxr.mozilla.org/mozilla/source/security/nss/lib/ckfw/builtins/certdata.txt?raw=1
in a web browser to avoid the chicken-and-egg problem with mk-ca-bundle's
built-in downloading, and then running "mk-ca-bundle.pl -n".

Note that we were not affected by the recently-fixed curl bug
(https://github.com/bagder/curl/commit/51f0b798fa), but only because
it had been so long since we had updated this file.
Merge pull request #874 from skazhy/clear-all-cookies-custom-domain

Allow deleting all cookies on custom domains
Add comments for domain and path arguments to cookie-clearing methods.
Update next-release notes.
Document Windows support (or lack thereof).

Closes #871.
Emphasize and clarify docs for AsyncHTTPClient.close.
Document the fact that the {% module %} directive requires a RequestHandler.

Closes #880.
Add a distinct exception for writing a WebSocket message on a closed connection.

This replaces an AttributeError on NoneType.

Closes #879.
In add_callback, hold the lock while writing to the waker pipe.

This protects against a shutdown race condition seen occasionally in
the ThreadedResolver unittests.  This slightly increases contention
on the callback lock in multi-threaded scenarios, but the cost is
limited by the fact that we only write to the pipe once per IOLoop
iteration.

Closes #875.
Add top level LICENSE file

Simlpe commit to add the Apache License, Version 2.0 to the top level
directory.

Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>
Merge pull request #889 from pabelanger/temp/license

Add top level LICENSE file
Check for empty strings and zero bytes in is_valid_ip.

Closes #893.
Bump verison number to 3.2.dev2