Fix DoS if refreshing of matview takes too long

Refreshing the view after many changes (such as the 8 million new torrents
in 2.0) can take, if the disk is a bottleneck, take longer than 60 min.

crawl-rss/main.go

@@ -45,7 +45,7 @@ func main() {
 			}
 		}
 		i++
-		go refresh(db)
+		refresh(db)
 		time.Sleep(time.Minute * 60)
 	}
 }