Move app to components

src/components/App.js

@@ -0,0 +1,18 @@
+import React, {Component} from 'react';
+
+class App extends Component {
+  render() {
+    return (
+      <div className="App">
+        <div className="container">
+          <div className="row">
+            <div className="three columns">First column</div>
+            <div className="nine columns">Next column</div>
+          </div>
+        </div>
+      </div>
+    );
+  }
+}
+
+export default App;

src/components/App.test.js

@@ -0,0 +1,9 @@
+import React from 'react';
+import ReactDOM from 'react-dom';
+import App from './App';
+
+it('renders without crashing', () => {
+  const div = document.createElement('div');
+  ReactDOM.render(<App />, div);
+  ReactDOM.unmountComponentAtNode(div);
+});