Added some more debug logging, and fixed a serious bug with the session...

Added some more debug logging, and fixed a serious bug with the session clean() method that caused bridging to not work properly as the cached requestID also was cleaned :)

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@244 44740490-163a-0410-bde0-09ae8108e29a