default outcome values to 0 if missing
default outcome values to 0 if missing

test plan:
* import the d2l export referenced in the ticket
 (before we actually fix the converters)
* visit the outcomes
* should not get missing value notices on page

refs #CNVS-5047

Change-Id: I8e0d44a764e476f3c9c03943d1c2105d41192a75
Reviewed-on: https://gerrit.instructure.com/19410
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>
QA-Review: Adam Phillipps <0e18f44c1fec03ec4083422cb58ba6a09ac4fb2a@instructure.com>
Product-Review: Bracken Mosbacker <48b846001bca4166dc3fb7711563afc17525921e@instructure.com>

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