Auth_State: Add support for exception handling.
Auth_State: Add support for exception handling.

This patch introduces infrastructure for throwing exceptions within
authentication modules and processing filters, and later catching them
in the application which uses the filters.
vivekrajenderan/simplesamlphp,vivekrajenderan/simplesamlphp,tectronics/simplesamlphp,vivekrajenderan/simplesamlphp,tectronics/simplesamlphp,vivekrajenderan/simplesamlphp,tectronics/simplesamlphp,vivekrajenderan/simplesamlphp,tectronics/simplesamlphp,tectronics/simplesamlphp