Feature/windows fix

This implements a Windows compatible ffmpeg output reading.
Based on [](http://stackoverflow.com/questions/375427/non-blocking-read-on-a-subprocess-pipe-in-python), it fixes https://github.com/sampsyo/audioread/issues/8 .

The solution is not perfect as it read the whole ffmpeg output with the given blocksize.
Ideally we should only read the needed datas to be yield.

Windows is not my primary OS so there may be bugs.

I also updated the setup method in setup.py to use setuptools, allowing the 

    python setup.py develop

command. I can make another PR if this is a problem.