Add setup.py

[M4rtinK]

Hi, I'd lake to package pyqver for Fedora, so I've added a setup.py and also removed the .py extension for the scripts, so that they can conform the usual CLI utility conventions.

Let me know if there are any issues with the pull request. :)

[JoshRosen]

+1. I'd really appreciate it if you published pyqver on PyPi, or at least added a setup.py so that I could install pyqver in one line using pip (pip install -e git+https://github.com/ghewgill/pyqver#egg=pyqver)

[techtonik]

.py extensions it needed on Windows.