Register API complete, email validation too

migrations/2_users.down.sql

@@ -1 +1 @@
-DROP TABLE IF EXISTS users;
+DROP TABLE IF EXISTS `users`;

migrations/2_users.up.sql

@@ -1,5 +1,6 @@
 CREATE TABLE IF NOT EXISTS `users` (
     `uuid` BINARY(16) PRIMARY KEY,
+    `created_at` DATETIME NOT NULL,
     `username` VARCHAR(64) NOT NULL,
     `password` VARCHAR(60) NOT NULL,
     `email` VARCHAR(255) NULL DEFAULT NULL,