add idle test (convert from jasmine)

lib/dialects/mysql/connector-manager.js

@@ -76,7 +76,7 @@ module.exports = (function() {
         if (self.pendingQueries === 0) {
           setTimeout(function() {
             self.pendingQueries === 0 && self.disconnect.call(self);
-          }, 1);
+          }, 100);
         }
       }
     });