added function to end connection

index.js

@@ -92,6 +92,17 @@ DB.prototype.execute = function (query, params) {
     });
 };
 
+/**
+ * Run DB execute
+ * @param  {String} query
+ * @param  {Object} [params]
+ * @return {Promise}
+ */
+DB.prototype.end = function() {
+    var db = this;
+    db.end();
+};
+
 module.exports = function(name) {
     name = name || '_default_';