PromoteImageReviewTask

@scottrabin 
This task suffered from being executed on wikis that didn't have the required extensions enabled. This refactor makes it pretty much exactly like https://github.com/Wikia/app/blob/dev/extensions/wikia/ImageReview/modules/PromoteImage/PromoteImageReviewTask.php.
The `(new \Wikia\Tasks\AsyncTaskList()))->...` syntax is jarring. I realize it's not yours, but it would be nice to separate out the object creation from the manipulation.