Python 2.7 adds B&D checks which break for the C wrapper.

This version passes all tests except the one which asserts that the proxy
can lie about its '__class__', which can't be done in Python.

Move narrative doctests out to Sphinx.

Convert non-narrative doctestss to unittests.

Move doctest examples to API reference.

Installs 'Sphinx' and dependencies.

Runs 'setup.py develop' plus installs 'nose' and 'coverage'.

Replace deprecated 'zope.interface.implements' usage with equivalent
'zope.interface.implementer' decorator.

As 'setuptools' is a dependency 'pkg_resources' will be available always. Ref: http://mail.zope.org/pipermail/zope-dev/2009-March/035277.html