Setuptools support

I'd like to use shyaml as a dependency in a project I maintain that uses setuptools for installation. Currently, installing shyaml through `pip`, `easy_install` or `python setup.py install` fails for me.

I used `pysetup generate-setup` to generate a backwards-compatible setup.py. It reads the configuration dynamically from setup.cfg, so it doesn't require any maintenance.

One change I did have to make was to the `description-file` setting in setup.cfg: it caused setup.py to make this call:

```python
open(u'README.rst CHANGELOG.rst', 'r')
```

Which obviously fails. `CHANGELOG.rst` doesn't exist anyway, so I removed it. That's what commit e9fd16da5d is for.
It'd be great if this update could be merged in and pushed to pypi.