add class for pruning metatags

app/logical/daily_maintenance.rb

@@ -1,6 +1,7 @@
 class DailyMaintenance
   def run
     PostPruner.new.prune!
+    TagPruner.new.prune!
     Upload.delete_all(['created_at < ?', 1.day.ago])
     ModAction.delete_all(['created_at < ?', 3.days.ago])
     Delayed::Job.delete_all(['created_at < ?'], 1.day.ago)

app/logical/tag_pruner.rb

@@ -0,0 +1,7 @@
+class TagPruner
+  def prune!
+    Tag.without_timeout do
+      Tag.destroy_all(["post_count <= 0 and name like '%:%'"])
+    end
+  end
+end