recalculate due dates and scores on user split
recalculate due dates and scores on user split

Change-Id: Ie1c82860bade123958ac381f2afa5dd637d67f9d
Reviewed-on: https://gerrit.instructure.com/171077
Reviewed-by: Keith Garner <a1a80143a840c140f31c3495ebbd9ec906e09fed@instructure.com>
Tested-by: Jenkins
QA-Review: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>
Product-Review: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>

instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms