Change to rate book import

When importing a rate book in XML format, that XML can now include a rate table definition with additional parameters. Previously, adding a parameter resulted in an import error. You can add parameters but you cannot remove parameters.

For example this can occur when you need to update a rate table definition in multiple instances. In one instance of PolicyCenter, you update the rate table definition by adding a new parameter, then export the containing rate book to XML. You then import that XML to second PolicyCenter instance.