added legacy support change and submit events in ie 6/7/8

This is a simple fix for issue #7. It adds support for change and submit events in legacy ie browsers which don't support event bubbling on them. It uses a simple trick by catching the first focus event on the element and then attaching the callback to the correct event.
It seems a bit odd that you're attaching three events here, you have line 37, line 42, and the later, line 47. Can you explain further what's going on here? Some comments would help.