Timing of 'chosen:showing_dropdown' fixed

Currently the event is triggered before dropdown LI's
are created. This commit corrects it by moving the
trigger event at end of method. A JSFIDDLE was created
to demonstrate the issue.

http://jsfiddle.net/lagrz/3A5jq/

By moving the event it enables developers to add
whatever additional code or styling to the dropdown
menu options such as images.

coffee/chosen.jquery.coffee

@@ -224,14 +224,14 @@ class Chosen extends AbstractChosen
       return false
 
     @container.addClass "chosen-with-drop"
-    @form_field_jq.trigger("chosen:showing_dropdown", {chosen: this})
 
     @results_showing = true
 
     @search_field.focus()
     @search_field.val @search_field.val()
 
     this.winnow_results()
+    @form_field_jq.trigger("chosen:showing_dropdown", {chosen: this})
 
   update_results_content: (content) ->
     @search_results.html content