Add a setup.py script

[danilobellini]

A setup script is missing for this project.

The installation could include a fractal script, besides the python -m fractal command.

Also, it would be nice to include an update to README.rst to use the new entry point in the examples, as well as installation instructions.

Tox wouldn't run the test suite the same way it does today, as skipsdist wouldn't be required anymore.

[danilobellini]

This was addressed by this commit.

It's still missing some important stuff like installation instructions and an image URL converter to use the URL from the GitHub repository on the egg PKG-INFO metadata. Perhaps the README generator script may be re-used by the setup script for creating the long description metadata.

Should the package name be kept fractals with the trailing s? The module file (and therefore the entry point) doesn't have an s, should it get an extra s?

The fractal script weren't add, but should it really be included? It's probably easier than python -m fractal, but that's clearly not required.