allow factory girl into tests

This adds factory girl methods (such as create, that creates an
object and saves it) to be found by all tests.

Signed-off-by: Zeljko <zeljko@zwr.fi>
rails g scaffold manufacturer

Modified test setup to fit for factory girl.

Signed-off-by: Zeljko <zeljko@zwr.fi>
rails g scaffold car_brands

same modifications for factory girl

Signed-off-by: Zeljko <zeljko@zwr.fi>