Ruby-saml allows attackers to perform XML signature wrapping attacks

ruby-saml prior to version 1.3.0 is vulnerable to an XML signature wrapping attack in the specific scenario where there was a signature that referenced at the same time 2 elements (but past the scheme validator process since 1 of the element was inside the encrypted assertion). ruby-saml users must update to 1.3.0, which implements 3 extra validations to mitigate this kind of attack.