Work on BrickPi packaging.

- Markdown-ified the README file

- Added Python packaging metadata

  This commit adds a "setup.py" file, allowing BrickPi.py to be installed
  using the normal Python installation methods (e.g., "python setup.py install"
  or "easy_install ." or "pip install .", etc).
Merge pull request #16 from larsks/master

Work on BrickPi packaging.