Log Message:
Update py-requests-toolbelt to 0.5.0.

Add test dependencies. All tests pass.

0.5.0 -- 2015-11-24
-------------------

More information about this release can be found on the `milestone
<https://github.com/sigmavirus24/requests-toolbelt/issues?utf8=%E2%9C%93&q=is%3Aall+milestone%3A0.5+>`_
for 0.5.0.

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

- The ``tee`` submodule was added to ``requests_toolbelt.downloadutils``. It
  allows you to iterate over the bytes of a response while also writing them
  to a file. The ``tee.tee`` function, expects you to pass an open file
  object, while ``tee.tee_to_file`` will use the provided file name to open
  the file for you.

- Added a new parameter to ``requests_toolbelt.utils.user_agent`` that allows
  the user to specify additional items.

- Added nested form-data helper,
  ``requests_toolbelt.utils.formdata.urlencode``.

- Added the ``ForgetfulCookieJar`` to ``requests_toolbelt.cookies``.

- Added utilities for dumping the information about a request-response cycle
  in ``requests_toolbelt.utils.dump``.

- Implemented the API described in the ``requests_toolbelt.threaded`` module
  docstring, i.e., added ``requests_toolbelt.threaded.map`` as an available
  function.

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

- Now papers over the API differences in versions of requests installed from
  system packages versus versions of requests installed from PyPI.

- Allow string types for ``SourceAddressAdapter``.