Handle descriptors defined in PyProxyBase subclasses the same way the C version does. This fixes #5.

[ci skip]

[ci skip]

See: http://blog.travis-ci.com/2014-12-17-faster-builds-with-container-based-infrastructure/

Downloaded from http://downloads.buildout.org/2/bootstrap.py

Try to preemptively answer hypothetical questions like Why can't I just

```
    class Proxy(object):
        def __init__(self, obj):
            self.__obj = obj
        def __getattr__(self, a):
            return getattr(self.__obj, a)
        def __setattr__(self, a, v):
            setattr(self.__obj, a, v)
```

Test this case under both Python 2.7 and 3.3.

  ``PyProxyBase._wrapped.__iter__`` if available, otherwise fall back to
  Python internals. The previous implementation always created a generator.

- Fixed ``PyProxyBase.__setattr__()`` to allow setting of properties on the
  proxy itself. This is needed to properly allow proxy extensions as was
  evidenced int he ``zope.security.decorator`` module.

- Denominate files to indicate ReST.

- Drop .bzrignore.

- Add MANIFEST.in FBO users w/o setuptools_git.

except under Python 2.6.
    
  N.B.  This change is an ABI incompatibility under Python 2.7:
        extensions built under Python 2.7 against 4.0.x versions of
        ``zope.proxy`` must be rebuilt.
  
Bump target version to '4.1.0' to signal BBB issue.

Enable compilation of dependent modules under Py3k.