title: Rails 4: collection_select not inserting 'class' attribute?
body: <p>What am I missing here? I am working with Rails 4.0.0 and trying out the new Bootstrap 3.0.0rc1. I have a simple 'recipe box' app that has a Recipe model and a Category model that feeds a 'category' field on the Recipe. In the recipes#new view, I have the following fields defined:</p>
  
  <pre><code>&lt;h1&gt;Create New Recipe&lt;/h1&gt;
  &lt;%= form_for @recipe, html: { class: 'form-horizontal' } do |f| %&gt;
  &lt;fieldset&gt;
    &lt;legend&gt;Main Information&lt;/legend&gt;
    &lt;div class="form-group"&gt;
      &lt;%= f.label :name, "Recipe name", class: "col-lg-2 control-label" %&gt;
      &lt;div class="col-lg-6"&gt;
        &lt;%= f.text_field :name, class: "form-control" %&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;div class="form-group"&gt;
    &lt;%= f.label :category_id, class: "col-lg-2 control-label" %&gt;
    &lt;div class="col-lg-6"&gt;
      &lt;%= f.collection_select :category, Category.all, :id, :name, class: "form-control", prompt: "Select a category" %&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  ...
  </code></pre>
  
  <p>The text_field helper renders a properly formatted  tag, complete with class attribute. However, no matter how I construct the select or collection_select helpers, I can't seem to get Rails to give me a  that contains a class attribute. The code above gives me this:</p>
  
  <pre><code>&lt;select id="recipe_category" name="recipe[category]"&gt;&lt;option value=""&gt;Select a category&lt;/option&gt;
  
  ...
  </code></pre>
  
  <p>So the prompt comes through, but the class attrib does not, so it looks like part of html_options hash is recognized. But the Bootstrap styling isn't applied. Doesn't matter if I use braces {} around the class: "form-control" or not. Doesn't matter if I use parens around the collection_select params or not. Happens with select helper as well.</p>
  
  <p>Can anyone advise? Are you seeing this too?</p>