Implemented more efficient storage of AuthnRequests in session. Instead of caching the complete request object, we now
cache an assoc array with the neccessary parameters. Both for SAML 2.0 and Shib 1.3.


git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@200 44740490-163a-0410-bde0-09ae8108e29a