Bind 'onKeyPress' during keydown instead of keyup.

Binding during keydown will be more effective at preventing certain default behavior like moving the page down as these events may happen prior to keyup. Addresses #1452
Merge branch 'patch-1' of github.com:songpete/video.js into songpete-patch-1
Merge branch 'songpete-patch-1'
Added a line to the change log for #1455