Show modal to inform login is required when adding Tags

Change-Id: Ib917ffd01fb3da04432ad588683d3c9077962199

src/app/stories/controller/story_detail_controller.js

@@ -21,7 +21,8 @@ angular.module('sb.story').controller('StoryDetailController',
     function ($log, $rootScope, $scope, $state, $stateParams, $modal, Session,
               Preference, TimelineEvent, Comment, TimelineEventTypes, story,
               Story, creator, tasks, Task, DSCacheFactory, User,
-              storyboardApiBase, SubscriptionList, CurrentUser) {
+              storyboardApiBase, SubscriptionList, CurrentUser,
+              SessionModalService) {
         'use strict';
 
         var pageSize = Preference.get('story_detail_page_size');
@@ -292,6 +293,13 @@ angular.module('sb.story').controller('StoryDetailController',
             );
         };
 
+        /**
+         * Show modal informing the user login is required.
+         */
+        $scope.showLoginRequiredModal = function() {
+            SessionModalService.showLoginRequiredModal();
+        };
+
         // ###################################################################
         // Task Management
         // ###################################################################

src/app/stories/template/detail.html

@@ -164,7 +164,12 @@
         </span>
         <h4>
             <span class="label label-default" ng-click="toggleAddTag()"
-                  ng-show="!showAddTag">
+                  ng-show="!showAddTag && isLoggedIn">
+                Add
+                <i class="fa fa-plus"></i>
+            </span>
+            <span class="label label-default" ng-click="showLoginRequiredModal()"
+                  ng-show="!isLoggedIn">
                 Add
                 <i class="fa fa-plus"></i>
             </span>