By adding a setup.py file, users may install cmpcodesize to their PATH,
by running `python utils/cmpcodesize/setup.py install`.
Should the Swift project choose to do so, this package may also be uploaded
to the Python Package Index (https://pypi.python.org/pypi). Doing so would
allow anyone with an Internet connection to install cmpcodesize by
running `pip install cmpcodesize`.
Setuptools also provides a convenient way to run unit tests (yet to be
added as of this commit).
