Update to 2.6.0 for a security issue.

2.6.0 (2015-03-14)
++++++++++++++++++

**Bugfixes**

- Fix handling of cookies on redirect. Previously a cookie without a host
  value set would use the hostname for the redirected URL exposing requests
  users to session fixation attacks and potentially cookie stealing. This was
  disclosed privately by Matthew Daley of `BugFuzz <https://bugfuzz.com>`_.
  An CVE identifier has not yet been assigned for this. This affects all
  versions of requests from v2.1.0 to v2.5.3 (inclusive on both ends).

- Fix error when requests is an ``install_requires`` dependency and ``python
  setup.py test`` is run. (#2462)

- Fix error when urllib3 is unbundled and requests continues to use the
  vendored import location.

- Include fixes to ``urllib3``'s header handling.

- Requests' handling of unvendored dependencies is now more restrictive.

**Features and Improvements**

- Support bytearrays when passed as parameters in the ``files`` argument.
  (#2468)

- Avoid data duplication when creating a request with ``str``, ``bytes``, or
  ``bytearray`` input to the ``files`` argument.


(wiz)