Changed 'versions' table creation to allow null values for 'effective_date' field.

This change was done in migration 048 but seems to have no effect with SQLite.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@611 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/001_setup.rb

@@ -214,7 +214,7 @@ class Setup < ActiveRecord::Migration
       t.column "project_id", :integer, :default => 0, :null => false
       t.column "name", :string, :limit => 30, :default => "", :null => false
       t.column "description", :string, :default => ""
-      t.column "effective_date", :date, :null => false
+      t.column "effective_date", :date
       t.column "created_on", :timestamp
       t.column "updated_on", :timestamp
     end