Prevent stacking notifications during rapid toggle

No issue
-Call notifications.closePassive after the resolution of the
 promise that generates the notifications. Otherwise multiple
 promises can stack up after notifications have been cleared,
 which results in a bunch of stacked notifications.
-Remove some unnecessary propagation of rejected promises from
 action handlers that can result in unhandled reject errors.

core/client/controllers/editor/new.js

@@ -11,7 +11,6 @@ var EditorNewController = Ember.ObjectController.extend(EditorControllerMixin, {
                 if (model.get('id')) {
                     self.transitionToRoute('editor.edit', model);
                 }
-                return model;
             });
         }
     }

core/client/controllers/posts/post.js

@@ -7,13 +7,12 @@ var PostController = Ember.ObjectController.extend({
             var featured = this.toggleProperty('featured'),
                 self = this;
 
-            self.notifications.closePassive();
-
             this.get('model').save().then(function () {
+                self.notifications.closePassive();
                 self.notifications.showSuccess('Post successfully marked as ' + (featured ? 'featured' : 'not featured') + '.');
             }).catch(function (errors) {
+                self.notifications.closePassive();
                 self.notifications.showErrors(errors);
-                return Ember.RSVP.reject(errors);
             });
         }
     }

core/client/controllers/settings/general.js

@@ -30,16 +30,14 @@ var SettingsGeneralController = Ember.ObjectController.extend({
         save: function () {
             var self = this;
 
-            self.notifications.closePassive();
-
             return this.get('model').save().then(function (model) {
+                self.notifications.closePassive();
                 self.notifications.showSuccess('Settings successfully saved.');
 
                 return model;
             }).catch(function (errors) {
+                self.notifications.closePassive();
                 self.notifications.showErrors(errors);
-
-                return Ember.RSVP.reject(errors);
             });
         },
     }

core/client/controllers/signin.js

@@ -12,6 +12,7 @@ var SigninController = Ember.Controller.extend(Ember.SimpleAuth.LoginControllerM
             this.validate({ format: false }).then(function () {
                 self.send('authenticate');
             }).catch(function (errors) {
+                self.notifications.closePassive();
                 self.notifications.showErrors(errors);
             });
         }