Editor: Warn if title change is unsaved

closes #3643
- TitleScratch is compared with Title; if there’s a difference, we have
unsaved changes and open up the modal.

mixins/editor-base-controller.js

@@ -88,6 +88,8 @@ var EditorControllerMixin = Ember.Mixin.create(MarkerManager, {
 
         var model = this.get('model'),
             markdown = this.get('markdown'),
+            title = this.get('title'),
+            titleScratch = this.get('titleScratch'),
             scratch = this.getMarkdown().withoutMarkers,
             changedAttributes;
 
@@ -95,6 +97,10 @@ var EditorControllerMixin = Ember.Mixin.create(MarkerManager, {
             return true;
         }
 
+        if (titleScratch !== title) {
+            return true;
+        }
+
         // since `scratch` is not model property, we need to check
         // it explicitly against the model's markdown attribute
         if (markdown !== scratch) {