If first reference matches a special case, other references are not validated

Please see the following return:

https://github.com/yaronn/xml-crypto/blob/4d72940b0f0ada3a87468265b34768e8f77fd737/lib/signed-xml.js#L501

should not be there and should be replaced by a continue;

Actually, the whole if can be removed, since there's a second hash check afterwards ....