anchor.diff:  + Response 409 (application/json)
   
               {
  -                "message": "Email address already exists"
  +                "message": "Email address already exists."
               }
           
   ## Authentication [/authenticate]
  
positive.code:             {
                  "id": 1,
                  "url": "http://www.domain.name/resource_normalized_by_server.html",
                  "created_at": "2015-08-05 08:40:51+01:00",
                  "updated_at": "2015-08-05 08:40:51+01:00",
                  "tags": [
  
negative.code:             {
                  "id": 2
                  "url": "http://www.domain.name/resource_normalized_by_server_2.html",
                  "title": "Title 1",
                  "image": "http://url/to_image.jpg",
                  "created_at": "2015-08-05 08:40:51+01:00",
                  "updated_at": "2015-08-06 08:40:51+01:00",
                  "tags": [
  