add react-java-mysql application sample

Signed-off-by: Anca Iordache <anca.iordache@docker.com>

samples/react-java-mysql/frontend/src/app/reducers.js

@@ -0,0 +1,10 @@
+import { combineReducers } from 'redux';
+import { routerReducer } from 'react-router-redux';
+
+import whalesReducer from 'app/redux/whales';
+
+export const rootReducer = combineReducers({
+    router: routerReducer,
+
+    whales: whalesReducer,
+});