Difficulty selectbox in Studio (based on new XBlockAside functionality). Include:

- adaptation asides to be imported from the XML
- updating SplitMongo to handle XBlockAsides (CRUD operations)
- updating Studio to handle XBlockAsides handler calls
- updating xblock/core.js to properly init XBlockAsides JavaScript

cms/static/js/xblock_asides/structured_tags.js

@@ -0,0 +1,40 @@
+(function($) {
+    'use strict';
+
+    function StructuredTagsView(runtime, element) {
+
+        var $element = $(element);
+
+        $element.find("select").each(function() {
+            var loader = this;
+            var sts = $(this).attr('structured-tags-select-init');
+
+            if (typeof sts === typeof undefined || sts === false) {
+                $(this).attr('structured-tags-select-init', 1);
+                $(this).change(function(e) {
+                    e.preventDefault();
+                    var selectedKey = $(loader).find('option:selected').val();
+                    runtime.notify('save', {
+                        state: 'start',
+                        element: element,
+                        message: gettext('Updating Tags')
+                    });
+                    $.post(runtime.handlerUrl(element, 'save_tags'), {
+                        'tag': $(loader).attr('name') + ':' + selectedKey
+                    }).done(function() {
+                        runtime.notify('save', {
+                            state: 'end',
+                            element: element
+                        });
+                    });
+                });
+            }
+        });
+    }
+
+    function initializeStructuredTags(runtime, element) {
+        return new StructuredTagsView(runtime, element);
+    }
+
+    window.StructuredTagsInit = initializeStructuredTags;
+})($);