i.e. bytestrings on Python 2, unicode on Python 3.
- Proxy URLs now *must* have an explicit scheme. A ``MissingSchema`` exception
will be raised if they don't.
+- Timeouts now apply to read time if ``Stream=False``.
- ``RequestException`` is now a subclass of ``IOError``, not ``RuntimeError``.
- Added new method to ``PreparedRequest`` objects: ``PreparedRequest.copy()``.
- Added new method to ``Session`` objects: ``Session.update_request()``. This