Re-add forgotten <author> element on standalone <entry>

app/lib/atom_serializer.rb

@@ -68,6 +68,9 @@ class AtomSerializer
     append_element(entry, 'published', stream_entry.created_at.iso8601)
     append_element(entry, 'updated', stream_entry.updated_at.iso8601)
     append_element(entry, 'title', stream_entry&.status&.title)
+
+    entry << author(stream_entry.account) if root
+
     append_element(entry, 'activity:object-type', TagManager::TYPES[stream_entry.object_type])
     append_element(entry, 'activity:verb', TagManager::VERBS[stream_entry.verb])