Add new subscription
POST http://localhost:3000/api/v0/customers/1/subscriptions/
Request Body
{"title"=>"Magical Tea Package", "price"=>10.0, "status"=>"active", "frequency"=>"weekly", "customer_id"=>1, "tea_id"=>1}
POST http://localhost:3000/api/v0/customers/1/subscriptions/
{"title"=>"Magical Tea Package", "price"=>10.0, "status"=>"active", "frequency"=>"weekly", "customer_id"=>1, "tea_id"=>1}