Merchant Coupon Create

[jimmacur]

Create a new coupon for a merchant.

• [x] test
• [x] controller
• [x] route
• [x] possible sad paths
  • This Merchant already has 5 active coupons
  • Coupon code entered is NOT unique

status: 201
body:

{
  "data": {
    "id": "1",
    "type": "coupon",
    "attributes": {
      "name": "Buy One Get One 50",
      ...remaining attributes go here...
    }
  }
}