title: How to refresh in React Navigation
body: <p>Once I remove user token, user redirects to Login Page. However if I login with other user, the main page still shows the previous user information. </p>
  
  <p>This is because I didn't refresh the Main page. How can I re-initialize(?) Main Page manually in react-navigation?</p>
  
  <pre><code>MainPage(Logged in as 'matt') -&gt; Logout -&gt; LoginPage 
  -&gt; (here I want to refresh MainPage so it can be loaded once new user login) 
  -&gt; MainPage(Should be logged in as other user 'kobe')
  </code></pre>
  
  <p><strong>MainPage receive user JSON data via componentWillMount</strong></p>
  
  <pre><code>  componentWillMount() {
      // retrieve user data 
      this.props.retrieveCurrentUser(this.props.token);
    }
  </code></pre>
  
  <hr>
  
  <p>Just in case you need my code...</p>
  
  <p>1) This is Root navigation </p>
  
  <pre><code>const RootTabNavigator = TabNavigator ({
      Auth: {
        screen: AuthStackNavigator,
      },
      Welcome: {
        screen: WelcomeScreen,
      },
      Main: {
        screen: MainTabNavigator,
      },
    }, {
  </code></pre>
  
  <p>2) This is Auth Stack Navigator (Login Page)</p>
  
  <pre><code>export default StackNavigator ({
    Autho: {
      screen: AuthScreen,
    },
    SignUp: {
      screen: SignUpScreen,
    },
    SignUpBio: {
      screen: SignUpUserBioScreen,
    },
    SignUpUsername: {
      screen: SignUpUsernameScreen,
    },
  }, {
      header: null,
      headerMode: 'none',
      navigationOptions: {
        header: null
      },
      lazy: true
  });
  </code></pre>
  
  <p>3) This is Main TabNavigator</p>
  
  <pre><code>export default TabNavigator(
    {
      Feed: {
        screen: FeedScreen,
      },
      Stylebook: {
        screen: StylebookScreen,
      },
      Wardrobe: {
        screen: WardrobeScreen,
      },
      Noti: {
        screen: NotificationScreen,
      },
      Menu: {
        screen: MenuScreen,
      },
    }, {
     ...
  }
  </code></pre>