title: Add Attributes to Zend Form Multicheckbox
body: <p>I am trying to do something interesting with jquery and my forms. And it all boils down to being able to group elements together based on specific attributes. I have a multicheckbox with a bunch of options in it which is generating the following example output:</p>
  
  <pre><code>&lt;label for="xyz-nn"&gt;
   &lt;input type="checkbox" value="nn" id="xyz-nn" name="xyz[]"&gt;Doodle
  &lt;/label&gt;
  </code></pre>
  
  <p>Imagine that lots of times. Anywho, I want to add an attribute with a unique value to each checkbox, but using setAttrib("attributeName", "valueN") sets the attribute as the last value instead of a new value for each checkbox.</p>
  
  <p>The question is: how do I set a unique value for an attribute on each option?</p>