Enhance the checks for required PHP extensions.
Enhance the checks for required PHP extensions.

Added checks for Date/Time, JSON, cURL and Session.

sitya/simplesamlphp,sitya/simplesamlphp,simplesamlphp/simplesamlphp,sitya/simplesamlphp,jschlyter/simplesamlphp,ghalse/simplesamlphp,simplesamlphp/simplesamlphp,simplesamlphp/simplesamlphp,ghalse/simplesamlphp,jschlyter/simplesamlphp,simplesamlphp/simplesamlphp,jschlyter/simplesamlphp,ghalse/simplesamlphp,dnmvisser/simplesamlphp,dnmvisser/simplesamlphp,dnmvisser/simplesamlphp,jschlyter/simplesamlphp,ghalse/simplesamlphp,dnmvisser/simplesamlphp,jschlyter/simplesamlphp,sitya/simplesamlphp