Initial dev of sidebar
Finishes the support for the sidebar

I also remove the django-discover-runner since Django 1.6 has
it's own discover. There are few changes in the test_settings.py
because i want to be able to run the tests without having to
install grappelli-extesions by pip.
Update RADME.md
Add sidebar screenshot
Merge pull request #1 from raphapassini/sidebar

Implement support to sidebar in admin