Accepting options in fixtures

Refs #9 and #10

> Needs to make some unit tests, but it fix to me the #9
>
> ---
>
> I my case I want to manipulate `createdAt` and `updatedAt` values but for some reaction this is only possible when I do:
> 
> ```javascript
> // see second argument
> Call.build(data, { raw: true , isNewRecord: true })
> ```
> 
> In sequelize-fixtures the line just do an build and magically these fields are filled :stuck_out_tongue:
> 
> Maybe, if pass in `.json` file/array the options aka:
> 
> ```javascript
> { 'model':  'Call',
>   'data': { 'number': '+55 11 999 878 876' },
>   'options': { 'raw': true, 'isNewRecord': true }
> }
> ```