update position attributes when reordering module items
update position attributes when reordering module items

if you dragged a module item below another one and then
indented it, it would jump up to where it used to be
in the list.

fixes #3716

Change-Id: Ic3c5cbdc028f4976bbc55e006a454c4a266f48bf
Reviewed-on: https://gerrit.instructure.com/2204
Tested-by: Hudson <dfb64870173313a9a7b56f814c8e3b33e268497a@instructure.com>
Reviewed-by: Bracken Mosbacker <48b846001bca4166dc3fb7711563afc17525921e@instructure.com>

ShreniiNepal/shrenii_lmp,dgynn/canvas-lms,jay3126/canvas-lms,icelab/canvas,tgroshon/canvas-lms,leftplusrightllc/canvas-lms,ShreniiNepal/shrenii_lmp,nditech/red-innovadores-lms,Unow/canvas-lms,wimemx/Canvas,Unow/canvas-lms,utkarshx/canvas-lms,antoniuslin/canvas-lms,SwinburneOnline/canvas-lms,juoni/canvas-lms,samuels410/greatlakes-lms,instructure/canvas-lms,venturehive/canvas-lms,whalejasmine/canvas-lms,landonwilkins/canvas-lms,sdeleon28/canvas-lms,arrivu/qibla-ecampus,dgynn/canvas-lms,djbender/canvas-lms,samuels410/greatlakes-lms,ottenhoff/canvas-lms,parbros/red-innovadores-lms,Unow/ins,instructure/canvas-lms,antoniuslin/canvas-lms,djbender/canvas-lms,skmezanul/canvas-lms,loganrun/pincan,AndranikMarkosyan/lms,tgroshon/canvas-lms,usmschuck/canvas,wimemx/Canvas,Rvor/canvas-lms,ankithbti/canvas_lms,utkarshx/canvas-lms,juoni/canvas-lms,va7map/canvas-lms,Rvor/canvas-lms,arrivu/jigsaw-lms,sli7246/canvas_branch,fronteerio/canvas-lms,arrivu/hoodemo,sfu/canvas-lms,AndranikMarkosyan/lms,dgynn/canvas-lms,rup/Tarrax,redconfetti/canvas-lms,arrivu/hoodemo,juoni/canvas-lms,icelab/canvas,grahamb/canvas-lms,usmschuck/canvas,shidao-fm/canvas-lms,va7map/canvas-lms,shidao-fm/canvas-lms,landonwilkins/canvas-lms,eCNAP/CANVAS,grahamb/canvas-lms,roxolan/canvas-lms,arrivu/jigsaw-lms,nditech/red-innovadores-lms,faraazkhan/canvas,va7map/canvas-lms,jay3126/canvas-lms,jay3126/canvas-lms,narigone/canvas,arrivu/arrivu-lms,AndranikMarkosyan/lms,sfu/canvas-lms,djbender/canvas-lms,matematikk-mooc/canvas-lms,whalejasmine/canvas-lms,usmschuck/canvas,Jyaasa/canvas-lms,leftplusrightllc/canvas-lms,merichar/canvas-lms,skmezanul/canvas-lms,snehakachroo1/LSI_replica,gbleydon/canvas-lms,arrivu/qibla-ecampus,venturehive/canvas-lms,samuels410/greatlakes-lms,kyroskoh/canvas-lms,wye0220/shindig-canvas,sfu/canvas-lms,redconfetti/canvas-lms,HotChalk/canvas-lms,Rvor/canvas-lms,roxolan/canvas-lms,landonwilkins/canvas-lms,em2/canvas-lms,Unow/ins,grahamb/canvas-lms,efrj/canvas-lms,ankithbti/canvas_lms,whalejasmine/canvas-lms,Unow/ins,instructure/canvas-lms,parbros/red-innovadores-lms,arrivu/hiring-site,redconfetti/canvas-lms,gbleydon/canvas-lms,Unow/canvas-lms,SwinburneOnline/canvas-lms,leftplusrightllc/canvas-lms,fronteerio/canvas-lms,grahamb/canvas-lms,instructure/canvas-lms,arrivu/qibla-ecampus,shidao-fm/canvas-lms,merichar/canvas-lms,SwinburneOnline/canvas-lms,venturehive/canvas-lms,sdeleon28/canvas-lms,ottenhoff/canvas-lms,loganrun/pincan,rup/Tarrax,SwinburneOnline/canvas-lms,utkarshx/canvas-lms,Jyaasa/canvas-lms,dgynn/canvas-lms,leftplusrightllc/canvas-lms,arrivu/hoodemo,sli7246/canvas_branch,eCNAP/CANVAS,matematikk-mooc/canvas-lms,arrivu/hiring-site,roxolan/canvas-lms,sfu/canvas-lms,faraazkhan/canvas,arrivu/jigsaw-lms,landonwilkins/canvas-lms,narigone/canvas,Jyaasa/canvas-lms,utkarshx/canvas-lms,skmezanul/canvas-lms,sfu/canvas-lms,greyhwndz/canvas-lms,loganrun/pincan,narigone/canvas,greyhwndz/canvas-lms,Jyaasa/canvas-lms,Rvor/canvas-lms,matematikk-mooc/canvas-lms,HotChalk/canvas-lms,em2/canvas-lms,sfu/canvas-lms,kyroskoh/canvas-lms,ShreniiNepal/shrenii_lmp,skmezanul/canvas-lms,kyroskoh/canvas-lms,wrdsb/canvas-lms,eCNAP/CANVAS,rup/Tarrax,grahamb/canvas-lms,wye0220/shindig-canvas,ottenhoff/canvas-lms,kyroskoh/canvas-lms,AndranikMarkosyan/lms,wrdsb/canvas-lms,HotChalk/canvas-lms,nditech/red-innovadores-lms,instructure/canvas-lms,parbros/red-innovadores-lms,narigone/canvas,HotChalk/canvas-lms,sfu/canvas-lms,fronteerio/canvas-lms,faraazkhan/canvas,tgroshon/canvas-lms,gbleydon/canvas-lms,antoniuslin/canvas-lms,em2/canvas-lms,snehakachroo1/LSI_replica,antoniuslin/canvas-lms,usmschuck/canvas,tgroshon/canvas-lms,arrivu/arrivu-lms,ShreniiNepal/shrenii_lmp,wrdsb/canvas-lms,greyhwndz/canvas-lms,eCNAP/CANVAS,wimemx/Canvas,snehakachroo1/LSI_replica,djbender/canvas-lms,instructure/canvas-lms,arrivu/hiring-site,sdeleon28/canvas-lms,sli7246/canvas_branch,samuels410/greatlakes-lms,efrj/canvas-lms,efrj/canvas-lms,icelab/canvas,merichar/canvas-lms,venturehive/canvas-lms,jay3126/canvas-lms,va7map/canvas-lms,juoni/canvas-lms,greyhwndz/canvas-lms,fronteerio/canvas-lms,wye0220/shindig-canvas,ankithbti/canvas_lms,wrdsb/canvas-lms,whalejasmine/canvas-lms,efrj/canvas-lms,snehakachroo1/LSI_replica,instructure/canvas-lms,arrivu/arrivu-lms,roxolan/canvas-lms,sdeleon28/canvas-lms,redconfetti/canvas-lms,nditech/red-innovadores-lms,shidao-fm/canvas-lms,matematikk-mooc/canvas-lms