title: adding class and id in form_dropdown
body: <p>Is there any possible way of adding class and id attributes in form_dropdown of CodeIgniter?
  I tried <code>form_dropdown('name',$array,'class','id')</code> and it's not changing anything, please tell me how to implement it?</p>
  
  <p>Edited: <br>
  with my dropdown form like this <code>form_dropdown('name',$array,set_value('someValue'),'id="myId"');</code> if I see my source from my browser it's look like this <code>&lt;select name="provinsi" id="provinsi_id"&gt;</code>, but if I write like your way <code>form_dropdown('name',$array,set_value('someValue'),'class="myClass"','id="myId"');</code> than like this in my browser source <code>&lt;select name="provinsi" class="myClass"&gt;</code></p>
  
  <p>that was I mean<br>
  thank you</p>