implement Application and MarketingApp components, enhance routing and user context management (#194)

src/Application.jsx

@@ -0,0 +1,10 @@
+import App from './App.jsx'
+import Contexts from './contexts/Contexts.jsx'
+
+const Application = () => (
+  <Contexts>
+    <App />
+  </Contexts>
+)
+
+export default Application