Adding class/id to table

Hi, Cebe. Maybe you can add a `class`/`id` to the table.
Example:

```
{.class1 #id1 .class2}
| header_1 | header_2 | header_3 |
| :------- | :------- | :------: |
| text_1 | text_2 | text_3 |
```

Result:

``` html

header_1 header_2 header_3


text_1text_2text_3

```

My implementation based on your library turned out to be [dirty](https://github.com/romeo7/rock/blob/master/framework/core/markdown/Markdown.php#L124).