Add sign in, sign up, and upload forms

src/components/App/index.js

@@ -1,22 +1,32 @@
+import React, { Suspense } from 'react';
+import {
+  BrowserRouter,
+  Switch,
+  Route
+} from 'react-router-dom';
 import './App.css';
 
+const SignInForm = React.lazy(() => import('../SignInForm'));
+const SignUpForm = React.lazy(() => import('../SignUpForm'));
+const FileUploadForm = React.lazy(() => import('../FileUploadForm'));
+
 function App() {
   return (
-    <div className="App">
-      <header className="App-header">
-        <p>
-          File upload demo
-        </p>
-        <a
-          className="App-link"
-          href="https://reactjs.org"
-          target="_blank"
-          rel="noopener noreferrer"
-        >
-          Learn React
-        </a>
-      </header>
-    </div>
+    <Suspense fallback={"Loading..."}>
+      <BrowserRouter>
+        <Switch>
+          <Route path="/" exact>
+            <SignInForm />
+          </Route>
+          <Route path="/signup">
+            <SignUpForm />
+          </Route>
+          <Route path="/upload">
+            <FileUploadForm />
+          </Route>
+        </Switch>    
+      </BrowserRouter>
+    </Suspense>
   );
 }