Fix issue with onchange_callback in IE8 being called onKeyDown but not onKeyUp

Noticed in IE8 when I was formatting my text (underlining, highlighting, ect..) it was trigger the onchange_callback onkeydown.  This was an issue for me since our onchange_callback is used to update our backbone models.  The issue is the onkeydown send back what is there before the change actually happens.  

For example:  If I type

1234 the last event sends back 123 
1234 then delete 4 it sends back 1234

I looked at the undo manager and looked like there was a block of code to call the change callback, so I added that to the onKeyUp.  This solved the issue for me, and did not appear to create any other issues.