Added 404 route

frontend/scenes/Error404/Error404.js

@@ -0,0 +1,25 @@
+import React from 'react';
+import { Link } from 'react-router';
+
+import Layout from 'components/Layout';
+import CenteredContent from 'components/CenteredContent';
+
+class Error404 extends React.Component {
+  render() {
+    return (
+      <Layout
+        titleText="Not Found"
+      >
+        <CenteredContent>
+          <h1>Not Found</h1>
+
+          <p>We're unable to find the page you're trying to find the page you're accessing.</p>
+
+          <p>Maybe you want to try <Link to="/search">search</Link> instead?</p>
+        </CenteredContent>
+      </Layout>
+    );
+  }
+}
+
+export default Error404;