fix(dao): HSTORE checking like ENUM

This allows user can define HSTORE attribute directly.

define like this
```javascript
var Task = sequelize.define('Task', {
  title: Sequelize.STRING,
  description: Sequelize.TEXT,
  deadline: Sequelize.HSTORE
})
```

instead of 
```javascript
deadline: {
  type: Sequelize.HSTORE
}
```

I think I have to write a test case to reflect this?