Fixed error when calling hasOwnProperty on null/undefined when saving posts

refs 89a6bc683b

- `options` did not have a default value and it's always passed in. Added a default value of an empty object so we're not tripped up with null/undefined

ghost/admin/app/controllers/editor.js

@@ -670,7 +670,7 @@ export default Controller.extend({
     }).group('saveTasks'),
 
     // convenience method for saving the post and performing post-save cleanup
-    _savePostTask: task(function* (options) {
+    _savePostTask: task(function* (options = {}) {
         let {post} = this;
 
         const previousEmailOnlyValue = this.post.emailOnly;