Show max filesize of variations, rather than original file size.

The original file isn't always accessible, and can be of completely
different size than the downloadable variations. This is mostly appliccable
to videos.

pillar/web/nodes/routes.py

@@ -196,6 +196,10 @@ def view(node_id):
     if 'description' in node:
         node['description'] = attachments.render_attachments(node, node['description'])
 
+    # Overwrite the file length by the biggest variation, if any.
+    if node.file and node.file_variations:
+        node.file.length = max(var.length for var in node.file_variations)
+
     if request.args.get('format') == 'json':
         node = node.to_dict()
         node['url_edit'] = url_for('nodes.edit', node_id=node['_id'])