VOLDEV-34: Parse [[wikilinks]] in Forum/Wall log actions

Follow-up to #2224

@Grunny @michalroszka @hakubo
```$entry['displayname']``` is an HTML link, so it needs to be passed unescaped: https://github.com/Wikia/app/blob/dev/extensions/wikia/Wall/WallHistoryController.class.php#L192