Log Message:
Update to 0.4.0:

0.4.0 -- 2015-04-03
-------------------

For more information about this release, please see `milestone 0.4.0
<https://github.com/sigmavirus24/requests-toolbelt/issues/46>`_ on the
project's page.

New Features
~~~~~~~~~~~~

- A naive implemenation of a thread pool is now included in the toolbelt. See
  the docs in ``docs/threading.rst`` or on `Read The Docs
  <https://toolbelt.readthedocs.org>`_.

- The ``StreamingIterator`` now accepts files (such as ``sys.stdin``) without
  a specific length and will properly stream them.

- The ``MultipartEncoder`` now accepts exactly the same format of fields as
  requests' ``files`` parameter does. In other words, you can now also pass in
  extra headers to add to a part in the body. You can also now specify a
  custom ``Content-Type`` for a part.

- An implementation of HTTP Digest Authentication for Proxies is now included.

- A transport adapter that allows a user to specify a specific Certificate
  Fingerprint is now included in the toolbelt.

- A transport adapter that simplifies how users specify socket options is now
  included.

- A transport adapter that simplifies how users can specify TCP Keep-Alive
  options is now included in the toolbelt.

- Deprecated functions from ``requests.utils`` are now included and
  maintained.

- An authentication tool that allows users to specify how to authenticate to
  several different domains at once is now included.

- A function to save streamed responses to disk by analyzing the
  ``Content-Disposition`` header is now included in the toolbelt.

Fixed Bugs
~~~~~~~~~~

- The ``MultipartEncoder`` will now allow users to upload files larger than
  4GB on 32-bit systems.

- The ``MultipartEncoder`` will now accept empty unicode strings for form
  values.