Add cloudinaryUrl custom field

packages/vulcan-cloudinary/lib/modules/custom_fields.js

@@ -28,7 +28,26 @@ export const addCustomFields = collection => {
         blackbox: true,
         optional: true
       }
-    }
+    },
+
+    // GraphQL only
+    {
+      fieldName: 'cloudinaryUrl',
+      fieldSchema: {
+        type: String,
+        optional: true,
+        viewableBy: ['guests'],
+        resolveAs: {
+          type: 'String',
+          arguments: 'format: String',
+          resolver: (document, {format}, context) => {
+            const image = format ? _.findWhere(document.cloudinaryUrls, {name: format}) : document.cloudinaryUrls[0]
+            return image && image.url;
+          }
+        },
+      }
+    },
+
   ]);
   
 }