Revert unbinding of all event delegates.

This reverts the change introduced in #8. This fixes #14 and #12.

The code `$(document).off(undefined, '**')` breaks 3rd-party
script behavior where events are delegated outside a `document.ready`
wrapper, like Rails's jquery_ujs.

For instance, having code that looks like this will fail after
navigating to a second page:

    // [A]
    $(document).on('click', 'button', function() { ... })

...this is exactly how scripts like jquery_ujs binds its events, and is
prescribed in jQuery's documentation for [fn.live].

To get around it, some people may misguidedly wrap it in a
`document.ready` wrapper like so. This is inefficient: events will then
be bound and un-bound repeatedly as you navigate through pages.

    // [B]
    $(function() {
      $(document).on('click', 'button', function() { ... })
    });

Therefore, [A] should be the recommended solution. This fix makes [A]
work again, but breaks the behavior of [B].

[fn.live]: http://api.jquery.com/live/