added tests for Aged Brie
refactored tests to reduce duplication

also added test for Aged Brie
added tests for Sulfuras
added tests for backstage passes

All stated functionality has now been tested and confirmed. Begin the
refactoring!
begin refactoring item quality update logic

tested backstage passes and legendary items
completely refactored UpdateQuality

tested Aged Brie, normal items
implemented conjured item quality update logic
refactored normal item quality update logic

refactored to be consistent with conjured item logic
refactored conjured item quality updater

refactored conjured item quality updater to extend from normal updater
refactored item type lookup