notify docupdate if the flush is from a shutdown

services/real-time/app/coffee/DocumentUpdaterManager.coffee

@@ -40,7 +40,8 @@ module.exports = DocumentUpdaterManager =
 		logger.log project_id:project_id, "deleting project from document updater"
 		timer = new metrics.Timer("delete.mongo.project")
 		# flush the project in the background when all users have left
-		url = "#{settings.apis.documentupdater.url}/project/#{project_id}?background=true"
+		url = "#{settings.apis.documentupdater.url}/project/#{project_id}?background=true" +
+			(if settings.shutDownInProgress then "&shutdown=true" else "")
 		request.del url, (err, res, body)->
 			timer.done()
 			if err?