DBを直接削除しただけでは、マイグレーションはうまく動かない ref: http://qiita.com/uchiko/items/8ba85d9bba26bb2fa552

migrations.php

<?php
return array(
    'version' => 
    array(
        'app' => 
        array(
            'default' => 
            array(
            ),
        ),
        'module' => 
        array(
        ),
        'package' => 
        array(
            'auth' => 
            array(
            ),
        ),
    ),
    'folder' => 'migrations/',
    'table' => 'migration',
);

shell

$ php oil r migrate:down -v=0