Migrated relevant SAML2 tests from Olav Morken to PHPUnit
Require mcrypt extension for XML encryption
Fixed LogoutRequest test
Added test for Consent attribute
Refactor AuthnRequestTest
Added phpDoc to class
Merge pull request #4 from simplesamlphp/feature/tests-migration

Migrated relevant SAML2 tests from Olav Morken to PHPUnit