title: Insert one css class to select on Rails date_select
body: <p>I am using the method date_select to generate 3 html selects, day, month and year.
  But I need that each select has one class of CSS.</p>
  
  <p>I have not found on documentation how to pass parameters to helper, I tried several ways and nothing.</p>
  
  <p>Rails View:</p>
  
  <pre><code>&lt;%= f.date_select :birthday, :order =&gt; [:day, :month, :year], :start_year =&gt; 1910, :end_year =&gt; 2012, :html =&gt; {:class =&gt; ['day', 'month', 'year']} %&gt;
  </code></pre>
  
  <p>HTML output:</p>
  
  <pre><code>&lt;select id="poll_user_birthday_3i" name="poll_user[birthday(3i)]"&gt;
  &lt;select id="poll_user_birthday_2i" name="poll_user[birthday(2i)]"&gt;
  &lt;select id="poll_user_birthday_1i" name="poll_user[birthday(1i)]"&gt;
  </code></pre>
  
  <p>HTML output like I do:</p>
  
  <pre><code>&lt;select id="poll_user_birthday_3i" name="poll_user[birthday(3i)]" class="day"&gt;
  &lt;select id="poll_user_birthday_2i" name="poll_user[birthday(2i)]" class="month"&gt;
  &lt;select id="poll_user_birthday_1i" name="poll_user[birthday(1i)]" class="year"&gt;
  </code></pre>
  
  <p>Thanks!</p>