Refactored SiteMap to be generic
With this mechanism (in combination with the new sidebar) in place
adding a new entity to the site becomes very easy, rather than having
to add a lot of code to 'map.py', one can simply register with
the sitemap modules.
#!/usr/bin/env python
from django.core import management
if __name__ == "__main__":
management.execute_from_command_line()