Store attachments in subdirectories (#5298).

Existing files can be moved to their target subdirectories using rake redmine:attachments:move_to_subdirectories.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@10990 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/20121213084931_add_attachments_disk_directory.rb

@@ -0,0 +1,9 @@
+class AddAttachmentsDiskDirectory < ActiveRecord::Migration
+  def up
+    add_column :attachments, :disk_directory, :string
+  end
+
+  def down
+    remove_column :attachments, :disk_directory
+  end
+end