Adds version status to limit issue assignments (#1245).

Available version statuses are:
* open: no restriction
* locked: can not assign new issues to the version
* closed: can not assign new issues and can not reopen assigned issues

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@3020 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/20091108092559_add_versions_status.rb

@@ -0,0 +1,9 @@
+class AddVersionsStatus < ActiveRecord::Migration
+  def self.up
+    add_column :versions, :status, :string, :default => 'open'
+  end
+
+  def self.down
+    remove_column :versions, :status
+  end
+end