Replace FoodItem controller and model with a scaffold

This is the result of these commands:

rails destroy controller FoodItem
rails destroy model FoodItem
rails generate scaffold FoodItem name:string price:float photo_path:string cuisine:string restaurant_name:string harrys_choice:boolean
rake db:drop; rake db:migrate; rake db:seed

...plus a small modification to the welcome#index view to use the new
controller name (food_items, not food_item) when generating links to
item pages.