Hook up reordering children in the browser.

* NOTE: the new order is NOT saved to the server!

cms/static/coffee/src/views/module_edit.coffee

@@ -13,6 +13,16 @@ class CMS.Views.ModuleEdit extends Backbone.View
 
       # Load preview modules
       XModule.loadModules('display')
+      @enableDrag()
+
+  enableDrag: ->
+      # Enable dragging things in the #sortable div (if there is one)
+      if $("#sortable").length > 0
+        $("#sortable").sortable({
+          placeholder: "ui-state-highlight"
+          })
+        $("#sortable").disableSelection();
+
 
   save: (event) ->
     event.preventDefault()
@@ -32,6 +42,7 @@ class CMS.Views.ModuleEdit extends Backbone.View
   cancel: (event) ->
     event.preventDefault()
     CMS.popView()
+    @enableDrag()
 
   editSubmodule: (event) ->
     event.preventDefault()
@@ -42,3 +53,4 @@ class CMS.Views.ModuleEdit extends Backbone.View
             id: $(event.target).data('id')
             type: if moduleType == 'None' then null else moduleType
             previewType: if previewType == 'None' then null else previewType
+    @enableDrag()

cms/templates/widgets/sequence-edit.html

@@ -33,7 +33,7 @@
     <section class="modules">
       <ol>
         <li>
-          <ol>
+          <ol id="sortable">
             % for child in module.get_children():
             <li class="${module.category}">
               <a href="#" class="module-edit"