Add rspec.
Add banner model.
Add sample JS script.
Add banners controller.
Update JS to get JSON banner.
Add Site model and relation with Banner via Placement model.
Get random banner for a site.
Add sample images.
Add "active" banners functionality and show/remaininh counters.
Add seed data.
Rspec helpers.
Count banner clicks.
Simple admin with twitter bootstrap.
Clean up.