Python 3 compat random patches

Now, the ``eventlet.green.*`` and ``_fileobject`` are very provisional, they just let me actually run tests and find some other issues, feel free to completely rewrite.

Many errors I'm seeing now are related to ``makefile``/``open`` API changes, that may be challenging to acomodate (https://github.com/eventlet/eventlet/commit/2b2f0a96b44779c5b98c851c55d70ec5e46e41f9#diff-2cdf03ba20c950d3729e46336ce8763eR23 won't be enough I'm afraid).

http://hg.python.org/cpython/file/2.7/Lib/socket.py#l212
http://hg.python.org/cpython/file/3.4/Lib/socket.py#l193
Was there a specific reason to rename? I would like to import six and use `if six.PY2`. Is it worse in some way?