distributable package (added setup.py)

I've added a basic `setup.py` to made this software easily installable and distributable. 
Note I moved the code to a package called `tiling`, so the canonical `from tile` turns into `from tiling`

Also uses the pycairo drop-in replace [cairocffi](https://github.com/SimonSapin/cairocffi) which is much more easy to install and better documented (pycairo can't be installed via pip/ inside a virtualenv)

you should register and upload it to pypi. See [this](https://pythonhosted.org/an_example_pypi_project/setuptools.html#registering-your-project)