Merge pull request #4 from haypo/trollius

With this second change, greentulip works on Python 2 (with Trollius) and Python 3 (with Trollius and Tulip)
Fix Task.current_task() related code
Fix unittests to work with asyncio
Fix examples to work with asyncio
Rename greentulip -> greenio
Remove last traces of Tulup (now asyncio)
Make setup.py ready for release on PyPI
Use default asyncio.SelectorEventLoop
port runtests.py to Python 2.7
port greenio to Python 2 and Trollius
port tests to Python 2 and Trollius