Except for todo.js, all the other examples on the homepage use React.autoBind
when defining event handler methods.
Test Plan: Added todo items successfully
onInput has the advantage that it responds to repeated key events before
onKeyUp and is called when modifying the input without the keyboard
(such as pasting with the mouse).
Test Plan:
Opened the ballmer-peak example and docs homepage in Chrome and checked
that both examples update whenever the text is changed.
