set up demo, exercise, final folders

step1-07/final/src/components/TodoListItem.tsx

@@ -0,0 +1,21 @@
+import React from 'react';
+import { TodoItem } from '../TodoApp.types';
+
+interface TodoListItemProps extends TodoItem {
+  id: string;
+  complete: (id: string) => void;
+}
+
+export class TodoListItem extends React.Component<TodoListItemProps, any> {
+  render() {
+    const { label, completed, complete, id } = this.props;
+
+    return (
+      <li className="todo">
+        <label>
+          <input type="checkbox" checked={completed} onChange={() => complete(id)} /> {label}
+        </label>
+      </li>
+    );
+  }
+}