Migration generator fixes.

Even though JSON permission handling is being phased out, I still had issues seeding my database (even though I wasn't using the JSON method). I recieved: 

```
  [Exception]
  SQLSTATE[42S22]: Column not found: 1054 Unknown column 'permissions' in 'field list' (SQL: insert into `roles` (`name`, `permissions`, `updated_at`, `created_at`) values (?, ?, ?, ?)) (Bindings: array (
    0 => 'Authorized',
    1 => 'null',
    2 => '2013-05-25 06:26:52',
    3 => '2013-05-25 06:26:52',
  ))

```