remove "track external right clicks" feature

db/migrate/20180729092926_remove_track_external_right_clicks.rb

@@ -0,0 +1,9 @@
+class RemoveTrackExternalRightClicks < ActiveRecord::Migration[5.2]
+  def up
+    execute "DELETE FROM site_settings WHERE name = 'track_external_right_clicks'"
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end