added setup.py


I created setup.py by following `django-fixture-magic` 's setup.py

I put `e git://github.com/kirelagin/django-orderedmodel.git@540cec38efc744ab53e8e9a40b37d19d3ac28a7e#egg=django-orderedmodel` in my requirements.pip and `pip install -r requirements.pip` correctly installs the django-orderedmodel.

This is my first time to create `setup.py` so there might be some missing pieces.