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

Signed-off-by: Georgy Berdyshev - Георгий Бердышев <codingmaster@gmail.com>

Signed-off-by: Georgy Berdyshev - Георгий Бердышев <codingmaster@gmail.com>

changelog entries (see http://svn.zope.org/*checkout*/Sandbox/philikon/foundation/releasing-software.txt)

  some of the fields.

- Bug: The behavior of tuples and lists in the `__getslice__()` and
  `__setslice__()` method were incorrect by not honoring the pre-cooked
  indices. See http://docs.python.org/ref/sequence-methods.html.