For mysql driver, when using pool, use con.release() instead of con.end() (if defined) (closes #335)

Author: dresende

lib/Drivers/DML/mysql.js

@@ -53,7 +53,11 @@ Driver.prototype.connect = function (cb) {
 	if (this.opts.pool) {
 		return this.db.pool.getConnection(function (err, con) {
 			if (!err) {
-				con.end();
+				if (con.release) {
+					con.release();
+				} else {
+					con.end();
+				}
 			}
 			return cb(err);
 		});
@@ -218,7 +222,11 @@ Driver.prototype.poolQuery = function (query, cb) {
 		}
 
 		con.query(query, function (err, data) {
-			con.end();
+			if (con.release) {
+				con.release();
+			} else {
+				con.end();
+			}
 
 			return cb(err, data);
 		});