Sends a nav event whenever the sideMenu button is clicked. (Android) (#617)

* Dispatch a navigation event whenever the side menu button is clicked (BottomTabsLayout)

* Dispatch a navigation event whenever the side menu button is clicked (SingleScreenLayout)

* Changed the way the navigatorEventId is retrieved in SingleScreenLayout.

android/app/src/main/java/com/reactnativenavigation/layouts/BottomTabsLayout.java

 
     @Override
     public void onSideMenuButtonClick() {
+        final String navigatorEventId = getCurrentScreenStack().peek().getNavigatorEventId();
+        NavigationApplication.instance.getEventEmitter().sendNavigatorEvent("sideMenu", navigatorEventId);
         if (sideMenu != null) {
             sideMenu.openDrawer(Side.Left);
-        } else {
-            final String navigatorEventId = getCurrentScreenStack().peek().getNavigatorEventId();
-            NavigationApplication.instance.getEventEmitter().sendNavigatorEvent("sideMenu", navigatorEventId);
         }
     }
 }

android/app/src/main/java/com/reactnativenavigation/layouts/SingleScreenLayout.java

 
     @Override
     public void onSideMenuButtonClick() {
+        final String navigatorEventId = stack.peek().getNavigatorEventId();
+        NavigationApplication.instance.getEventEmitter().sendNavigatorEvent("sideMenu", navigatorEventId);
         if (sideMenu != null) {
             sideMenu.openDrawer(Side.Left);
-        } else {
-            final String navigatorEventId = stack.peek().getNavigatorEventId();
-            NavigationApplication.instance.getEventEmitter().sendNavigatorEvent("sideMenu", navigatorEventId);
         }
     }
 }