First step to Python 3 compatibility
"2to3 -w -f except ." See [1]

[1] http://docs.python.org/2/library/2to3.html#fixers

- generic forwarder written for socket and OpenSSL.SSL objects.
In OpenSSL.__init__ instead of overwriting methods on the object level
with GreenSSLConnection methods, these methods are deleted. After that regular class methods are visible.
Backdor forwarder changed to look simmilar to socket forwarder.

All usage of e[0] replaced with either get_errno(e) or e.args[0] if intnetion was not to extract errno, but first argument

- __import__ used to import system modules in places where local module with the same name exist.
- GreenSocket.timeout private member renamed to _timeout. It is R/O property in 3.x socket.socket object.
- Calls to GreensSocket.timeout changed to call gettimeout to isolate clients from GreenSocket internals.
- GreenSocket access to unknown attributes will be forwarded to fd member. i.e. py3k has _io_refs property not needed in 2.x version
- get_errno moved to eventlet/greenio.py to be accessible to every place where testing socket.error.errno is needed
- Modified tests to use makefile with mode='w' where data was written. 3.x does not allow to write to file opened for reading.
- socket._fileobject class does not exist in 3.x. It will be emulated with _fileobject function. Also moved definition from eventlet.green.socket to eventlet.grreenio.