Expose IOStream's max_buffer_size, so we can set it in TCPServer and others.
Corrected or logic to make use of max_buffer_size if it is setted
change bind_unused_port to pass None as port

bind_unused_port was passing 0 as port number to the socket module.
This generated some exceptional behaviour on systems where nslookup of
localhost didn't returned the loopback interface.
Add note about frequently-seen pull request to add **kwargs to json_encode.
Merge pull request #777 from mauriciosl/master

bind_unused_port raising gaierror: [Errno 8]
Added note regarding regex group capture to StaticFileHandler docs.
Merge pull request #783 from gwk/master

Add note about handler regex capture to StaticFileHandler documentation.
Move _UIModuleNamespace from the top of web.py to the UIModule implementation.
Add a distinct MissingArgumentError class for get_argument.

Closes #782.
Add a run_with_stack_context function to more easily use stack contexts in coroutines.
Don't log EPIPE (broken pipe) errors as warnings

Broken pipe errors are usually caused by connection reset, and its better to not log EPIPE errors to minimize log spam
Add a 'plus' argument to url_{un,}escape, defaulting to True.

Closes #25.
Use plus=False when constructing and decoding url paths.
Merge pull request #784 from tahajahangir/patch-1

Don't log EPIPE (broken pipe) errors as warnings
Check for ECONNRESET in addition to EPIPE on send().

ECONNRESET appears to be the error code used here on Windows.

Closes #757.
Closes #758.
Merge pull request #748 from wsantos/fix732

Add max_buffer_size argument to TCPServer's constructor
Release note and doc updates
Don't try sending another error response in _handle_request_exception
if the stack context catches an error after the request is done.

(this may be related to the error discussed in the comments of #751)
Allow prepare to be asynchronous, and detect coroutines by their result.

The prepare method does not use the @asynchronous decorator, only
@gen.coroutine (or @return_future; it detects the Future return type).
The same logic is now available for the regular http verb methods as well.

Closes #605.
Allow handlers to assign to self.current_user