idp/SSOService: Use SAML2 library for parsing authentication requests.
idp/SSOService: Use SAML2 library for parsing authentication requests.

sgomez/saml2,madmatt/saml2,newmen/saml2,ArtemTeleshev/php-saml2,simplesamlphp/saml2,sitya/saml2,cb8/saml2