addEventListener requires 3 parameters in old browsers

This pull request adds the `useCapture` parameter when calling `addEventListener` for socket.io to be able to run on Firefox < 6.

As stated in the [Mozilla documentation](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget.addEventListener):
> Note: useCapture became optional only in more recent versions of the major browsers; for example, it was not optional prior to Firefox 6. You should provide this parameter for broadest compatibility.