User Story: Sale/Subscription Discounts

[DarrachBarneveld]

As a User, I can get sales and member discounts so that I can get items at a better price

Acceptance Criteria:

1. Users get discounted price on sale items
2. Users get discounted price when members
3. Users get discount if membership is in cart
4. Price breakdown is clearly presented

Tasks

• [x] Create subscription discount functions
• [x] Add methods to order model to account for discounts
• [x] Reflect all discounts in cart and checkout UI
• [x] The total accounts for final price

[DarrachBarneveld]

Subscription discounts are shown in confirmation, cart and checkout