Add migration, model, factory, and spec file for Organization
Add migration, model, factory, and spec file for Campaign
add presence and unique validations to Organization
Add migration, model, factory, and spec file for Donor
Add migration, model, factory, and spec file for Item
Add migration, model, factory, and spec file for Pledge
Add migration, model, factory, and spec file for Request
create associations between models
make aliases for Item model