Clean up.

- Renamed virtualenv_slingsby -> venv_slingsby
- Removed some unused files (indexes to old datastore)
- Moved some logic away from slingbsy __init__ file to main.py
- Updated version of django debug toolbar (no recent release in pypi)
- Updated admin login page to django 1.5 style, updated the redirect url.
- Make manage.py work again.
Delay slingsby import in main.py to after sys.path modification.
Add grunt-pylint.
Add a .pylintrc and delint