Put back database_cleaner setup
Bring back seeds for orgs and sites
Merge pull request #5 from alphagov/seed-org-site

Bring back seeds for orgs/sites/hosts

It's hard (prior to any CRUD) to get any acceptance of new features when they depend 
on data that's not there. This brings seed data back (and specs it this time, 
and avoids submodules into the bargain)