remove openobject in content_zipper
remove openobject in content_zipper

OpenObject has been replaced by a struct in order to gain performance.

test plan:
  - create an eportfolio
  - download a zip of the eportfolio
  - make sure the extracted zip contents are correct

Change-Id: Ibe8cbbacd154ba4cbc3a09180beb73e214cb8549
Reviewed-on: https://gerrit.instructure.com/16050
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: Brian Palmer <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@instructure.com>
QA-Review: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>

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