honor maxConcurrentQueries configuration option

lib/sequelize.js

@@ -51,7 +51,8 @@ module.exports = (function() {
       host    : this.options.host,
       port    : this.options.port,
       pool    : this.options.pool,
-      protocol: this.options.protocol
+      protocol: this.options.protocol,
+      maxConcurrentQueries: this.options.maxConcurrentQueries
     }
 
     var ConnectorManager = require("./dialects/" + this.options.dialect + "/connector-manager")