Support extra query arguments along with query destination and during registration

If you start on a url that has a query string, after you have authenticated using bakery and logged in, the query string will be lost. I think we need to store this in the cookie data, so that we can pass these additional query parameters to drupal_goto().

Here is an initial patch. This is rolled against a site and not the bakery module, as I don;t have the repo checked out atm, sorry :)