Update json.lib.php

http://www.dolibarr.fr/forum/3-installation/51023-erreur-sur-page-d-accueil-dans-les-boite-graphique

If we have \" in $out like array(\"year\" => \"2014\",\"showtot\" => \"on\") we have : Parse error: syntax error, unexpected '"', expecting T_STRING in /dolibarr/htdocs/core/lib/json.lib.php(248) : eval()'d code on line 1