Packaging for pypi

I had to change a bit the repository layout.

I've created a `visvalingam/` directory to store code for the package itself. 

I've also added an `example/` directory to keep the example itself (json and html). 

The `simplify.py` script is now in the `bin/` directory (as usual on pypi). This type of packaging will allow end-user to use it as a standard file of `/usr/bin/` and it will automatically be flaged as executable.

The readme had been rewritten using the restructuredtext syntax (it's basically the same content as before, I just changed the link to the sc. paper that was dead).

Finally, concerning setup.py, I referenced you as the author (fields `author` and `author_email`) and I as the maintainer (for the pypi package). If you want to maintain the package yourself, i can give it back to you.

Thank you for this implementation !