Various setup.py enhancements.

- PEP8 fixes
- Use setuptools.find_packages()
- Update PyPI classifiers
- Update website URL
- Install the argparse module in Python 2.6 and before
- Delete the duplicate rply in install_requires. With the PyPI
  version, tests are failed.
Merge branch 'patch-1' of https://github.com/berkerpeksag/hy into berkerpeksag-patch-1