api-ref: Replace image-update response example

The image-update sample response in the current api-ref is a bit
weird (too many null values).  This patch replaces it with a more
typical response.

Change-Id: I1f837d8fa0e42b9f9f1c421555339924d72cb9fe
Closes-bug: #1606253

api-ref/source/v2/samples/image-update-response.json

@@ -1,23 +1,24 @@
 {
-    "id": "da3b75d9-3f4a-40e7-8a2c-bfab23927dea",
+    "checksum": "710544e7f0c828b42f51207342622d33",
+    "container_format": "ovf",
+    "created_at": "2016-06-29T16:13:07Z",
+    "disk_format": "vhd",
+    "file": "/v2/images/2b61ed2b-f800-4da0-99ff-396b742b8646/file",
+    "id": "2b61ed2b-f800-4da0-99ff-396b742b8646",
+    "min_disk": 20,
+    "min_ram": 512,
     "name": "Fedora 17",
-    "status": "active",
-    "visibility": "public",
-    "size": 2254249,
-    "checksum": "2cec138d7dae2aa59038ef8c9aec2390",
-    "tags": [
-        "fedora",
-        "beefy"
-    ],
-    "created_at": "2012-08-10T19:23:50Z",
-    "updated_at": "2012-08-12T11:11:33Z",
-    "self": "/v2/images/da3b75d9-3f4a-40e7-8a2c-bfab23927dea",
-    "file": "/v2/images/da3b75d9-3f4a-40e7-8a2c-bfab23927dea/file",
+    "owner": "02a7fb2dd4ef434c8a628c511dcbbeb6",
+    "protected": false,
     "schema": "/v2/schemas/image",
-    "owner": null,
-    "min_ram": null,
-    "min_disk": null,
-    "disk_format": null,
+    "self": "/v2/images/2b61ed2b-f800-4da0-99ff-396b742b8646",
+    "size": 21909,
+    "status": "active",
+    "tags": [
+        "beefy",
+        "fedora"
+    ],
+    "updated_at": "2016-07-25T14:48:18Z",
     "virtual_size": null,
-    "container_format": null
+    "visibility": "private"
 }