correctly handle empty POST parameters
Factor argument replacement logic out of @return_future
Add a Future-based interface to tornado.auth's twitter_request.

This allows new clients to receive exception messages from failed
requests, without breaking compatibility with existing callback-based
clients.
Add future interface to most of the rest of the auth module.

_oauth_get_user still uses callbacks internally, and I haven't
changed the old deprecated FacebookMixin.
Use the future interface internally for _oauth_get_user.

Added a new method _oauth_get_user_future because the old method was
de facto public for third-party auth plugins.
Centralize some shared logic bewteen HTTPClient implementations.
Add a test for simple_httpclient's hostname_mapping.
Make simple_httpclient's hostname_mapping a Resolver wrapper.
simple_httpclient._HTTPConnection now takes a resolver directly.

This makes the "client" parameter optional for websocket connections.
Add a future-based interface to AsyncHTTPClient.fetch.
Make Resolver Configurable and test with a threaded resolver.
Make Resolver's callback argument optional when the Future result is used.
Ensure the result variable is initialized even when an exception is handled.
Add pypi classifiers so we'll show up on python3-compatible lists.
Rename local var so it doesn't shadow the "list" built-in.
Fix docstrings quoting.
Merge pull request #683 from vkosh/master

Unshadow list built-in in httputil.HTTPHeaders.get_all()
Exceptions in a @return_future function go to both the caller and the Future.

Add a test for the UnboundLocal error seen here and remove the
no-longer-needed initialization.  I'm not 100% sure we want to do both
(due to the risk of callback-doubling), but the old way where the caller
saw one error and the future resolved to a different error was clearly
incorrect, and leaving the future unresolved doesn't seem right either.
Test the @return_future return value assertion and move it again.
Remove timeout callback on errors during connect or request.