Fixes the migration 008 is irreversible

Author: vividtone

db/migrate/008_change_default_bugfix_on_view_customizes.rb

@@ -1,6 +1,10 @@
 class ChangeDefaultBugfixOnViewCustomizes < ActiveRecord::CompatibleLegacyMigration.migration_class
-  def change
+  def up
     change_column_default :view_customizes, :path_pattern, ""
     change_column_default :view_customizes, :comments, ""
   end
+
+  def down
+    # Leave the default values unchanged
+  end
 end