Allow user to set attributes for assets tags.

For your purposes you can pass additional attributes to helpers `js` and `css`.

    != css('normalize', { media: 'print', data: { 'turbolinks-track': function(){return true} } })
    or
    != css('normalize', { media: 'print', 'data-turbolinks-track': true })

Result:
    
    <link rel="stylesheet" href="/css/normalize.css" media="print" data-turbolinks-track />