U4-855 Embed Media - allow inserting custom HTML into Source tab

src/Umbraco.Web.UI/umbraco_client/tinymce3/plugins/umbracoembed/dialog.htm

@@ -76,7 +76,7 @@
             <div id="source_panel" class="panel">
                 <fieldset>
                     <legend>{#embed_dlg.source}</legend>
-                    <textarea id="source"></textarea>
+                    <textarea id="source" onkeydown="UmbracoEmbedDialog.changeSource();"></textarea>
                 </fieldset>
             </div>
         </div>    

src/Umbraco.Web.UI/umbraco_client/tinymce3/plugins/umbracoembed/js/dialog.js

@@ -77,6 +77,16 @@ var UmbracoEmbedDialog = {
         if ($('#url').val() != '') {
             UmbracoEmbedDialog.showPreview();
         }
+
+    },
+    changeSource: function (type) {
+        if ($('#source').val() != '') {
+            $('#insert').removeAttr('disabled');
+        }
+        else {
+            $('#insert').attr('disabled', 'disabled');
+        }
+
     }
 };