Utilities: Updated addURLparameter to merge the new query string with the old query string.
Utilities: Updated addURLparameter to merge the new query string with the old query string.

This should fix a problem where one can end up with multiple parameters with
the same name in the query string. This patch also changes the $parameter of
addURLparameter to be an associative array. For backwards compatibility it can
still be a string.


Rud5G/simplesamlphp,Rud5G/simplesamlphp,Rud5G/simplesamlphp,Rud5G/simplesamlphp