added exception logging for federation lookups
added exception logging for federation lookups

The exceptions were simply swallowed when something failed during
the lookups. This commit adds some logs to ease debugging.

dnmvisser/simplesamlphp,dnmvisser/simplesamlphp,ghalse/simplesamlphp,dnmvisser/simplesamlphp,dnmvisser/simplesamlphp,simplesamlphp/simplesamlphp,ghalse/simplesamlphp,simplesamlphp/simplesamlphp,simplesamlphp/simplesamlphp,simplesamlphp/simplesamlphp,ghalse/simplesamlphp,ghalse/simplesamlphp