Correct setup.py

Fixes [stevejalim pull request](https://github.com/roverdotcom/django-inlinecss/pull/3) by adding `packages=find_packages()` to setup.py.
With stevejalim changes and my additional commit, django-inlinecss can be installed via pip. Example: 

    pip install git+https://github.com/fjsj/django-inlinecss.git@18f2f8e5b5453f067dff0d6c0c2ae3066e56d554`

Without my additional commit, the app won't be installed correctly. See: http://stackoverflow.com/questions/16604994/how-to-install-use-django-inlinecss/