The coupon_codes table will allow for administrators to create new promo
codes associated with coupon information (amount, duration, etc...).
A user will be able to enter a promo code (aka coupon code) in order to
apply a new coupon to their account. The coupon in the coupons table is
linked to the template defined in the coupon_codes table.
Change-Id: I50e49fa92afbc6aa9d01d8a895c069efb59e472b
