Sortable bugfix

Sortable bugfix


I don't intend to do much for the project but I fixed this since it
kept giving me errors everywhere. I guess the programmer never noticed
it or something or I'm being stupid, but it fixed all the errors for
me.
When you've changed something in the sortable item the error will
appear that
$(this.helper).outerWidth() is not a function (or something)
change outerWidth() to offsetWidth and outerHeight() to offsetHeight
(which is just after the first replacement).
Hope this is of some use to someone.