correctly handle empty POST parameters
Add a comment to runtests.sh about python 3.

Closes #612.
Added period check in PeriodicCallback

If a user currently passes in 0ms (hopefully by accident) as the
callback time for a periodic callback, Tornado consumes a huge amount
of CPU and never calls the function.
Added more sensical callback time verification.
AsyncHTTPTestCase no longer closes AsyncHTTPClients on the global IOLoop.

Code that uses the global IOLoop may retain a global reference to
an AsyncHTTPClient as well, which would become inoperable after a test
had closed it.
simple_httpclient: Treat 302 like 303.

Cherry-picked from https://github.com/bergundy/tornado/commit/e49b263de2f4aa7b9748531b2ccf6b50b28b1bd5

Closes #623.
Release notes for 302/303 change.
Mv README so github web interface recognize its markup language
Add a helpful __repr__ implementation to URLSpec.
Allow add_handlers() to append to existing hosts.

This change removes the restriction that all handlers for a given host
pattern be registered in a single call to add_handlers().
Fix a bug with IOStream.read_until_close with a streaming_callback.

If the underlying socket was already closed the buffered data
would be passed to the final callback rather than the streaming callback.
Merge pull request #624 from pablopda/master

Move README so github web interface recognize its markup language
Merge pull request #627 from jparise/urlspec-repr

Add a helpful __repr__ implementation to URLSpec.
Fix TwitterMixin on Python 3.

Also add tests, and add get_auth_http_client method to all auth mixins.

Closes #634.
Ensure that add_callback fails cleanly if called while IOLoop is closing.

Previously there would (sometimes) be an exception when writing to the
waker pipe.

Closes #635.
Fix a memory leak in stack_context.

The old_contexts reference in StackContexts could maintain a chain of
old irrelevant contexts, so clear it once it's no longer needed.
This was mainly a problem in gen.engine, where additional contexts
would accumulate in memory (but not on the stack) for each asynchronous
operation.

Also clear the deactivate_stack_context in gen.Runner to allow
the StackContext to be garbage-collected sooner.
Fix If-None-Match support for StaticFileHandler.

No longer set Cache-Control: public on static files; redbot.org says
it generally doesn't do anything useful.
Make header_callback behavior consistent across both HTTP clients.

SimpleAsyncHTTPClient now sends the first and last lines to the callback,
matching CurlAsyncHTTPClient's behavior.

All secondary callbacks are now wrapped for stack_context.

Closes #637.
Merge branch 'master' into append-handlers
_get_host_handlers() now returns all host matches.

This approach has more clearly defined precedence rules than the
previous insertion-time strategy implemented in add_handlers().

It also correctly leaves pattern matching in the hands of the regular
expression evaluator as opposed to directly comparing pattern strings.