StepUiBuilder do not enclose groups in parent element

This allows the caller to handle how to group and render steps.  But we do
add another container to hold each of the groups.

src/ui/step/StepUi.js

@@ -263,7 +263,7 @@ module.exports = Class( 'StepUi' )
     /**
      * Returns the generated step content as a jQuery object
      *
-     * @return jQuery generated step content
+     * @return {jQuery} generated step content
      */
     getContent: function()
     {

src/ui/step/StepUiBuilder.js

@@ -162,9 +162,8 @@ module.exports = Class( 'StepUiBuilder' )
         // enclose it in a div so that we have a single element we can query,
         // making our lives much easier
         ui.setContent(
-            $( '<div class="raterStepDiv" />' )
-                .attr( 'id', '__step' + ui.getStep().getId() )
-                .html( data.content.html )
+            $( '<div class="step-groups" />')
+                .append( $( data.content.html ) )
         );
 
         // free the content from memory, as it's no longer needed (we don't need