get the last author from the last message, not the stream item
get the last author from the last message, not the stream item

Change-Id: I3092383b8898f17f7bf1f4c97fb113f322f3797d
Reviewed-on: https://gerrit.instructure.com/16337
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Tested-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

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