Add foundation styling to button elements

well, for the `ButtonType`, you cannot specify behavior in Symfony [(see here)](http://symfony.com/doc/current/reference/forms/types/button.html).
You can change the type to `reset` , to render a button with `type="reset"`, (a `ResetType`) but cannot add links

But you have various options:
* add an `onClick` tag to the `attr` array
* add a class `link`, a tag `data-url` to the `attr` array and let jQuery handle it

You want me to add a piece of information to the readme?