python3 compat fixes; Thanks to Astrum Kuo

https://github.com/eventlet/eventlet/pull/82

Celery could work with eventlet in Python3 now
greenthread: add .unlink() method; Thanks to Astrum Kuo

Compatibility with gevent.
https://github.com/eventlet/eventlet/pull/82
green: subprocess: do not use `new` module for compatibility with Python3

Module `new` was removed in python 3 so we should
remove it's usage due to py3 compability

https://github.com/eventlet/eventlet/pull/87