Adds :shallow option to resource route definition. If true, paths for nested
resources which reference a specific member (ie. those with an :id parameter)
will not use the parent path prefix or name prefix.
Example :
map.resources :users, :shallow => true do |user|
user.resources :posts
end
* GET /users/1/posts (maps to PostsController#index action as usual)
named route "user_posts" is added as usual.
* GET /posts/2 (maps to PostsController#show action as if it were not nested)
Additionally, named route "post" is added too.