ogcp: add checksum to images in Manage cache

Ease detection of potential problems with images in cache.
Show checksum under each image in the form.

ogcp/templates/actions/cache.html

@@ -39,6 +39,7 @@
                             {{ image.image_name() }}
                             {{ image.clients() }}
                             <b>{{ image.image_name.data  }} ({{ (images_data[image.selected.label.text]['size'] | int / 2**20)|round(3) }} MiB)</b>
+                            <div>∘︎ Checksum: {{images_data[image.selected.label.text]['checksum']}}</div>
                         </td>
                         <td>
                           {% for ip in images_data[image.selected.label.text]['clients'] %}

ogcp/views.py

@@ -1211,6 +1211,7 @@ def action_client_cache():
                         'clients': [ip],
                         'size': int(image_info['size']),
                         'name': image_name,
+                        'checksum': checksum
                     }
 
             storage_data[ip] = {'used': used_cache,