[U] Update app component usage

src/components/app/app.ts

@@ -23,9 +23,6 @@ export default class App extends Vue
     courses: Course[] = [];
     gradedCourses: Course[] = [];
 
-    // The currently selected tab
-    selectedTab: string = 'overall';
-
     // Token
     user: LoginUser = null as any;
 

src/components/app/app.vue

@@ -3,8 +3,8 @@
         <login v-if="showLogin" v-on:login:user="onLogin"/>
         <navigation v-if="user != null"
                     :courses="gradedCourses"
-                    :activeIndex.sync="selectedTab"
                     :user="user"
+                    :nav="navigator"
                     @sign-out="signOut" @select-time="selectTime">
         </navigation>