Create a command to add a new site

[veselosky]

Adding a new site requires multiple steps:

1. Install a new Apache vhost for the site.
2. Add the site domain to ALLOWED_HOSTS
3. Add a record in the Django Sites table
4. Reload Apache to pick up the new config
5. Restart Django/gunicorn to pick up the change to ALLOWED_HOSTS
6. Create a Home Page for the new site