Log Message:
Update py-requests to 2.9.1.

2.9.1 (2015-12-21)

Bugfixes

* Resolve regression introduced in 2.9.0 that made it impossible
  to send binary strings as bodies in Python 3.
* Fixed errors when calculating cookie expiration dates in certain
  locales.

Miscellaneous

* Updated bundled urllib3 to 1.13.1.