Allow user to unset custom note value.

js/plugins/reference_footnotes/plugin.js

@@ -102,10 +102,10 @@ CKEDITOR.plugins.reference_footnotes = {
             realElement = origElement;
         }
 
-        if (text && text.length > 0 )
+        if (text && text.length > 0 ) {
             realElement.setText(text);
-        if (value && value.length > 0 )
-            realElement.setAttribute('value',value);
+        }
+        realElement.setAttribute('value',value);
 
         var fakeElement = editor.createFakeElement( realElement , 'cke_reference_footnote', 'hiddenfield', false );
         editor.insertElement(fakeElement);