Jetty HttpServer add factories to avoid NPE
Jetty HttpServer add factories to avoid NPE

Add default factories to servlet/errorPageMapping properties to avoid NPE if they haven't been configured.

foam-framework/foam2,foam-framework/foam2,foam-framework/foam2,jacksonic/vjlofvhjfgm,jacksonic/vjlofvhjfgm,foam-framework/foam2,jacksonic/vjlofvhjfgm,foam-framework/foam2