title: change active menu icon color in DrawerNagivation react-native
body: <p>I m creating my first react-native application and i wanted to change css for drawer navigation.i have already tried changes color with activeTintColor but its not working.I just wanted to change the icon color or the menu item which is active.</p>
  
  <p>What i have done is here:</p>
  
  <pre><code>    const DrawerNavigation = createDrawerNavigator({
    Page1: {
      screen: MainTabNavigator,
      navigationOptions: {
        drawerLabel: 'Home'
      },
      contentOptions: {
        activeTintColor: 'rgb(234, 94, 32)'
      }
    },
    page2: {
      screen: AboutUs,
      navigationOptions: {
        drawerLabel: 'About Us'
      },
      contentOptions: {
        activeTintColor: 'rgb(234, 94, 32)'
      }
    },
    Page3: {
      screen: LogoutScreen,
      navigationOptions: {
        drawerLabel: 'Logout'
      },
      contentOptions: {
        activeTintColor: 'rgb(234, 94, 32)'
      }
    }
  },
  {
    initialRouteName: 'Page1',
    contentComponent: CustomDrawerContentComponent
  });
  </code></pre>