Refactor User model

[johnktravers]

What does this PR do?

• Replaces the worst_ingredients and best_ingredients methods in the User model with a sorted_ingredients method that takes flag and count arguments
• Replaces the worst_ingredient_data and best_ingredient_data methods with a to_data class method in the Ingredient model
• Updates tests accordingly (test coverage is still at 99.9%)
• Configures static assets using an Amazon Cloud Services CDN (unrelated - sorry for mixing this in)

Where should the reviewer start?

• With the sorted_ingredients method in the User model
• Then look at the to_data method in the Ingredient model

Thoughts/Refactors

• It occurred to me that sorted_ingredients is never called without mapping the ingredients to a hash with the to_data method, so just having one method that sorts the ingredients behind the scenes and returns the hash might be preferable
• I would love to hear your thoughts on how to improve this refactor!