Move setuptools' packaging configuration from setup.py to setup.cfg to
simplify setup.py and make its packaging more dedeclarative.
Signed-off-by: Satoru SATOH <satoru.satoh@gmail.com>
By releasing as a [Python wheel](http://pythonwheels.com/) as well as a
source distribution, you can speed up end user’s installs. After merging
this command, to release you just need to run `python setup.py clean
sdist bdist_wheel upload`.